Search

Two steers excreting similar quantities of organic matter daily were grazed at pasture during the summer of 1961. The four experiments each involved a preliminary period of five days dosing with Cr2O3 to reach a fairly constant excretion. The steers received a daily dose of Cr2O3 either in oil suspension or in shredded paper. The carriers and steers were interchanged for each trial. For two of the trials each steer in turn was harnessed every other day and all its dung collected in a bag. Total faecal excretion of organic matter was measured from the bagged steer and estimated from the Cr2O3 concentration in a composite sample made up from all dung pats voided during the ten-day collection period. In the other two trials the steers were not harnessed and each dung pat was separately sampled and analysed for Cr2O3 in the organic matter. The average recovery of Cr2O3 in the first two trials was 99·1 (oil) or 94·4% (paper). Calculating the faecal organic matter excretion from the concentration of Cr2O3 in the faeces and the quantity given daily overestimated it by 3·5 to 8·0%. There was no significant difference between shredded paper and oil as carriers of Cr2O3 for estimating the quantity of organic matter excreted. There were 37% and 22% less variation between dung pats in Cr2O3 concentration when this was administered in shredded paper than when given in oil suspension.

Investigations of paper-fiber sludge deposits in the Rainy River, Minnesota, below paper mills were made to determine water characteristics over them with reference to survival of walleye (Stizostedion v. vitreum) eggs and fry and occurrence of bottom fish-food organisms. Sampling of water from the fiber-sludge water interface to the surface showed gradients in oxygen as great as 0.1 ppm to near saturation, and in dissolved sulfides from 0.8 to 0.0 ppm. The most rapid gradient of these materials was in the bottom 20 mm. Levels of sulfides were most affected by current velocity and showed little relation to temperature or season. Walleye eggs placed in test trays on fiber mats had lower survival than those placed 12 inches above the mats and those placed on mineral substrates. Eggs and fry placed on mats died within 48 hours. Laboratory bioassays showed that sulfide levels of 0.3 ppm under controlled conditions approximating river conditions were acutely lethal to Gammarus pseudolimnaeus and walle...

Walleye fingerlings (Stizostedion v. vitreum) were held in 0, 50, 100, and 150 ppm conifer-groundwood fiber at 65 F and 100% oxygen saturation for up to 190 days. Fish were contained in recirculating water-flow systems and fed daily; water and fiber suspensions were changed daily. At the end of the experiment, fish in fiber were 2 to 3% shorter in length and 6 to 11% lighter in weight than controls. Relative condition factor was unchanged. Routine metabolic rate of walleyes in 150 ppm fiber was 18% higher than controls and active metabolic rate was 15% lower. Number of mucous cells on gills of fish from 150 ppm fiber treatments was 38% lower than controls and hematocrit of fish held in fiber averaged 6% lower than controls.

The method of preservation of forage tissue may influence the quality and quantity of the product. Oven drying with hot air is widely used; however, enzyme activity and respiration are stimulated during the moisture reduction process. Criterion for selecting efficient drying conditions, such as sample density, kind of container (cloth or paper), and size of container were investigated using alfalfa (Medicago sativa L.) herbage. The dry matter, total nonstructural carbohydrate (TNC), starch, reducing sugar, and nonreducing sugar percentages were related to drying rate. Drying rate was linear until 80% dry weight was reached. Conditions requiring no more than 15 hours to reach 80% dry wt (density of 12 g dry wt per liter for paper sacks) were needed to hold loss within limits of experimental error for estimation of dry weight percentage. The TNC in all oven-dried samples was less than in freeze-dried tissue; however, data from cloth bags showed less loss and carbohydrate interconversion than paper sacks. Conditions requiring no more than 8 hours to reach 80% dry wt (density of 7 g per liter for paper sack) were required for sufficiently rapid drying to limit loss and interconversions of nonstructural carbohydrates within limits of experimental error. About twice this density was acceptable if cloth bags were used since the drying tune was reduced by about one-half with cloth as compared to paper containers that had equal densities. Acceptable bulk densities will differ with efficiency of the drying equipment, but time needed for drying to 80% dry wt should not exceed these limits.

SUMMARY Water loss from cut grass was studied to determine factors limiting the drying process. An apparatus, used to measure water loss at 28±1°C from blotting paper and from leaves and stem internodes of cocksfoot, consisted of four channels in which air speed was controlled at 25–80 cm s-1 and relative humidity at 7–68%. The maximum rate of water loss from wet blotting paper was 10500 mg water dm-2 h-1 but from leaves and stem internodes supplied with water it was less than 250 mg dm-2 h-1. The rate of loss from both plant specimens and blotting paper was linearly related to the vapour pressure differences between the specimen and the surrounding air but was not increased when air speed was changed from 40 to 80 cm s-1. Grass specimens supplied with water had lower rates of water loss than wet blotting paper because of tissue resistances which were calculated for (a) untreated leaf and stem specimens, (b) rubbed leaves, (c) cut leaves, (d) leaves exposed to steam for 60 s. Treatments (b)-(d) greatly reduced tissue resistances. The rates of drying of leaves and stem internodes not supplied with water changed only slightly in response to faster air speeds but were significantly increased by treatments (b), (c), (cs) (split stems), (d) and (e) (exposure to petroleum vapour for 60 s). The most effective treatments trebled the drying rates of leaves and increased the drying rates of stem internodes by 10 times. Reductions in relative humidity had little effect on drying rate following treatments (a), (b), (c) and (d), but when treatments (cs) and (e) were given, additional significant increases in drying rates were obtained when the relative humidity was reduced. Grass specimens given the most effective treatments and dried under the most favourable conditions did not utilize the full drying capacity of the environment, for the rates of water loss from these specimens were at least three times lower than those from wet blotting paper. The results indicate that high rates of drying could be achieved at 28 oC or similar temperatures if practical treatments were developed to remove or greatly reduce the high resistance to water loss in cut grass.

While one of us (E. B. C., '31) was investigating the action of ultraviolet rays on the embryos of Lintax flavus Linnaeus, it was noticed that some batches of eggs were so dehydrated that they were wrinkled or had depressions in them. This condition prevailed if the eggs were laid in a dry or moderately damp receptacle. These eggs, however, would hatch if placed in a moist container. Khalil ('22) found that Planorbis corners were quite susceptible to drying, being killed in five hours when in a jelly-like mass. Adolph and Adolph ('25) placed Lumbricus terrestris in a 0.I36 M solution of sodium chloride for twenty hours and found that the worms would recover after a 35 per cent loss in weight. Jackson ('26) also, working on Lumbricus terrestris. found that they would live, after losing 43 per cent of their original weight in four to five hours, when placed on dry filter paper. Jackson found that they would die if they lost 50 to 6o per cent of their weight. Since the eggs of Limnax flavus Linnaeus hatched after being dehydrated enough to show a definite depression, we decided to perform a series of experiments to determine the maximum loss in weight which the young would survive and still be able to hatch. The eggs are fastened together by means of a membrane and thus all are laid at once. The slugs do not move while laying; hence the eggs become superimposed and are able to retain their moisture for a longer period than single eggs. The eggs varied considerably in weight: the maximum being 97.49 milligrams and the minimum being 5I.i6 milligrams. The average weight for I,200 eggs was found to be 78.7I milligrams. The eggs are elliptical in shape, the average diameter being about 0.5 centimeter and the average length being about 0.75 centimeter. They are covered with a rather tough membrane, which allows them to be moved on dry filter paper without being ruptured. A vitilline membrane surrounds the embryo, and this membrane is surrounded by a semi-fluid gelatinous mass, which resembles egg white. These experiments were conducted at room temperature (20 to 300 C.). The slug eggs, containing embryos from one to twenty-two days old, were weighed and subjected to dehydration. The eggs were placed on clean dry filter paper, the drying process lasting from two to seven hours. The eggs were weighed at the end of definite periods and placed in Petri dishes on moist filter paper. The weights given in this paper are averages in all cases.

Eggs of the slug, Limax flavus Linnaeus, lost weight very rapidly when placed on dry filter paper (Carmichael and Rivers, '32). The eggs were covered with a membrane which allowed this exchange of moisture. Since this membrane was not rigid it was decided to determine whether the weights of the eggs would remain the same until the time of hatching if they were allowed to be in contact with moist filter paper. Hayes ('30) found that the wet weight of salmon eggs increases slowly until a short time before hatching and then rapidly. The slug eggs were laid in the laboratory. After being separated and washed, they were placed on moist filter paper until they regained any weight which they had lost either during the time required for laying or in the case of those that were laid during the night, until they were observed the next day. Tap water was used for washing and for moistening the filter paper. The different batches of eggs were left on the moist filter paper for varied lengths of time previous to the first weighing, but the periods were always of several hours duration. The eggs, when laid, were fastened together by a connecting membrane and thus necessitated being separated before starting the experiment. After a few hours of preliminary moistening, the eggs were placed on dry filter paper for about thirty seconds in order to remove the external moisture. The eggs were weighed and placed back on moist filter paper. The above process of weighing was repeated at intervals of a day or more up to the time of hatching. Non-fertile eggs, as controls, were carried through the above procedures. Figure 1 illustrates the effects on the weights of fertile and non-fertile slug eggs which have remained in contact with moist filter paper. The data are averages of the weights of the eggs in whole batches and a single curve represents effects on one batch. The curves in figure 1 are given as representative ones of the several batches which have been observed. Several of the curves are somewhat irregular during the first few days of the experiment. There was a marked increase in the weight of the fertile eggs after about the eighth day, figure 1, A. This increase was accelerated until the eggs reached a maximum weight which occurred in most cases between the fifteenth and eighteenth days after being laid. Then there was usually a rapid loss in weight until the hatching began. When a majority of the eggs in a batch had hatched, the weighings were discontinued. As controls, non-fertile eggs were allowed to remain on moist filter paper for definite periods which correspond to the time required for hatching of fertile eggs, figure 1, B. The increases in the weights of the non-fertile eggs in 15 to 18 days were never as great as they were in the case of the fertile eggs. That the weights of most of the batches of control eggs given here are not the maximum weights that could have been attained is fairly certain since a majority of the curves show that the eggs were increasing in weight at the time these particular experiments were discontinued.

Homotypically conditioned media (Hom. C.M.) produced by adult Biomphalaria glabrata weighing about 600 mg and fed on pure cellulose under bacteriostatic conditions at a density of one snail per 100 milliliter of standard snail water for three days significantly enhanced the growth of juveniles. Hom. C.M. produced under the same conditions by fasting snails that were previously fed on lettuce, also had a growth promoting effect but was less potent. The growth promoting factors have a molecular weight of 500-104, and appear to act directly on the snails and not indirectly by influencing the food medium. The extent to which absolute growth rate is stimulated by the growth factors correlates well with decrements in the conductivity and calcium concentration of the media. Possible modes of action of the growth factors are discussed. They appear not to influence the relative weights of shell, or body and water content of the snails. It is suggested that the adaptive significance of the growth factors is to facilitate rapid increase in numbers of this gregarious and often fugitive species when environmental conditions are favorable.

Malathion uptake by six feed ingredients was investigated using stacks of small sack-cloth covered units, simulating surface samples from full bags, sprayed with a dispersible powder formulation at a rate equivalent to about 165 mg./sq. ft. For units stored at 30° and 70% R.H., apparent uptake was about 10% of the initial deposit for citrus pulp, soya-bean meal, cottonseed meal and groundnut meal, 30% for coconut meal and 50% for rice bran. These levels were reached after 5-9 weeks' storage, and did not vary greatly over the period of study (1-13 weeks post-spraying) except in rice-bran and coconut meal where the level increased markedly up to 9 weeks after spraying, but had decreased slightly by 13 weeks. No significant differences occurred between units stacked so as to simulate the under surface of a bag, and those simulating the upper surface. The differences in uptake between the various ingredients confirm the assumption that commodities with high oil-content are likely to be most susceptible to contamination. Supplementary comparisons for citrus pulp and coconut meal showed that apparent uptake was greater at 30° than at 20°, but the effect of a slightly lower storage humidity (63%) was not significant. The practical significance of these results in relation to the use of malathion water-dispersible powders for the control of insect infestation in bagged feed ingredients is discussed, and estimates of contamination likely to occur in full sacks are given.

At the Dickinson substation in North Dakota two-row hulled varieties of barley have produced larger yields than the other groups. Some of the data obtained on three groups of barley, the two-row hulled nodding bearded group, six-row hulled bearded group and the six-row naked hooded group in both plat and nursery trials are presented in this paper. An eight-year test, in field plats, of three varieties of barley representing the three groups named, shows that the two-row hulled variety outyielded the six-row hulled variety 32 percent and the six-row naked variety by 33.5 percent. There was a difference of 4 percent in yield between the six-row hulled variety and the six-row naked sort. The same three groups of barley, represented by 27 varieties, were grown in short rows in the nursery, during a period of five years, 1909 to 1913, and in the present paper a statistical study is made of the yield of both grain and straw, together with the percentage of grain in plant (excluding roots), and also height of plants, number of heads per plant, length of head and the duration of the growing period. The probable error is determined for the mean of each group for the five-year period. The groups are paired and their means and differences for the data given, together with their probable errors, are shown in graphs. The significance of the differences is determined by a comparison of the difference with its probable error. A difference three times greater than its probable error. A difference three times greater than its probable error is considered significant. Greater differences are credited to the inherent characters of the varieties. A summary of the significant differences expressed in percentages is given in Table 9, the others being omitted. The two-row hulled group exceeds the six-row hulled group in yield of grain by 43 percent; in yield of straw by 49.1 percent; has no significant difference in percentage of grain in plant or in height of plant; produces per plant 51.5 percent more heads, of 55 percent greater length, and requires a growing period 7.3 percent longer. The two-row hulled group exceeds the six-row naked group by 44.7 percent in yield of grain and 53.3 percent in yield of straw; has no significant difference in percentage of grain in the plant; produces 67.8 percent more heads, averaging 40.9 percent longer, and has a growing period 7.1 percent longer. On the other hand, the plants of the six-row naked group average 6.9 percent taller than those of the two-row hulled group. The six-row naked group has plants 8.1 percent taller and heads 10 percent longer than those of the six-row hulled group. The greater yield of both grain and straw in the two-row hulled group is accounted for, in part, by the greater number of heads per plant, the longer heads, and a longer growing period. The greater number of heads per plant is considered the most important factor. There are many other plant characters not included in this study that possibly may be determining yield factors but the data presented show some reasons why two-row hulled nodding bearded barleys produce greater yields than six-row hulled bearded or six-row naked hooded barleys at Dickinson.

If ecologists are to understand the relations of animals to environment, there must be more detailed knowledge of the chemistry of animals in relation to varying environmental factors. The present paper attempts to contribute to this general field by describing the variations in composition of two common fresh-water fishes, the yellow perch and the brook trout, at various ages, seasons, and tinder varying conditions of nutrition. Though many chemical analyses of parts of fishes have been made by those interested in their food value, no one has, to the knowledge of the writer, made analyses of entire fishes. Clark and Almy (i9i8) give a brief but excellent summary of the analytical work on fishes up to the time their paper was published. Most analyses have been concerned with the composition of the parts of fishes that are used as food for man; usually the muscular tissue of fresh, cold-storage, dried, smoked, or preserved fishes, and hence, though of interest to those concerned commercially or scientifically in dietetics, are of slight value to those who would study fishes from an ecological point of view. During the investigations described in this paper no fishes were analyzed that were not alive immediately before the analysis began. Each fish was killed by cutting through the body on the dorsal side behind the head so as to sever the spinal cord. The ventral body wall was then opened with scissors, the alimentary canal removed and all food stripped out of it. The entire fish, including the cleaned alimentary canal, was then cut up into pieces having a maxinmum size of about 2 cc. The pieces were placed together into a 4-inch watch glass, weighed, and kept in a Freas vacuum oven (at 6o0 C. and under a vacuum equal to 25 inches of mercury) until they were dry enough to show the same weight on two successive days. This required about three weeks. Each fish was then ground to powder in a mortar and again kept in the vacuum oven (about four days) until it maintained a constant weight. A representative sample, usually weighing about three grams, was then ashed in a platinum crucible in a Type FD-20i Haskins electric furnace at 5550 C. The remainder of the fish was sent to Dr. H. E. Schuette (i9i8), who determined the fats by ether extraction and the total nitrogen, using the Soxhlet and Kjeldahl-Cunning-Arnold methods. The brook trout analyzed were obtained from the Madison hatchery of

In a recent paper by Anslow it was concluded that there was no significant relationship between Leaf-area Index, light interception and growth rate in a perennial ryegrass sward. The author further concluded that higher growth rates would not be obtained by attention to this relationship. The data presented by Anslow are re-examined in this paper and the results of the analysis showed that: (a) recovery growth of the swards followed a sigmoid pattern of growth, (b) at low values of LAI growth rate was low and maximum growth rate was attained when most of the visible light was intercepted by leaves, and (c) the relationship between yield and LAI was linear, indicating that leaf-area increase after defoliation also followed a sigmoid pattern. These results are discussed in relation to Anslow's interpretation.

Although it has been generally agreed that the use of fat in poultry rations has some value, the scientific papers which have been published so far provide quite a number of contradictory results. This paper shows that where a proper balance is maintained between the various nutrients in the ration, particularly in the protein/total digestible nutrient ratio, high levels of fat consistently improve efficiency of feed conversion and growth rate.

Samples of eight soils were air-dried and stored in brown-paper or in sealed polythene bags for periods up to 98 weeks. Portions of the fresh and re-wetted air-dry soils were incubated at 25° for 10–84 days. the soils were extracted before and after incubation and the increase in mineral-N (NH4+-N + NO3−-N) content (Δ Mineral-N) was measured. Air-drying increased Δ Mineral-N. Air-dry storage further increased Δ Mineral-N, the value increasing with the period stored, but the mineralisable-N of soils kept in sealed polythene bags increased less than that of soils in paper bags, the increases occurring only in the easily mineralisable-N; most of the extra mineral-N was formed during the first 10 days incubation and all by 42 days, thereafter the air-dried soils had the same rate of mineralisation as the fresh soils. the mineral-N content of the air-dry soils increased with storage. In a further similar test with 14 soils, air-dried and stored in brown-paper bags for periods up to 32 weeks, the mean value of Δ Mineral-N varied irregularly with time of storage up to 18 weeks but thereafter increased with increasing period of storage before incubation. the mineral-N content of the air-dry soils varied, the maximum value being found in the samples stored for 12 weeks.

Youngest fully expanded leaves, from plants of M. officinali$ (L.) Lam. seeded at weekly intervals but harvested on the same day, were approximately 1.5 to 2.0 times as high in content of glucose, fructose, and sucrose at all stages of growth as leaves from comparable plants of M. infesta Guss. These plants varied in age from 3 to 14 weeks. Levels of glucose and fructose increased with increasing plant age in both species. Sucrose content increased in M. officinalis but decreased in M. infesta as the plants matured. When plants of approximately the same age were sampled at six different dates, the level of each sugar again was higher in young leaves of M. officinalis than in corresponding leaves of M. infesta at each sampling date. Evidence reported in this and preceding papers suggests that differences in sugar content may influence the degree of resistance or susceptibility of M elilotus leaves to feeding by the adult sweetc10ver weevil (Sitona cylindricollis Fahraeus), but that these differences apparently are not primarily responsible for the observed differences in resistance displayed by M. officinalis and M. infesta. Additional index words: Sitona cylindricoUis, Sugars, Insect resistance. F by the adult sweetclover weevil, Sitona cylindricollis (Fahraeus) was stimulated by a water-soluble fraction extracted from Melilotus leaves (4, 6). The feeding stimulant, designated Stimulant A, was found in chromatographically purified leaf extracts from the weevil-resistant Melilotus infesta Cuss., as well as from a susceptible species, M. officinalis (L.) Lam. Stimulant A was subsequently fractionated into three feeding stimulants which were identified as glucose, fructose, and sucrose (3). The isolated compounds and corresponding reagent grade sugars were identical in chromatographic and chemical behavior, and also in feeding stimulant activity as measured with the sweetclover root disk bioassay (7). Sucrose stimulated the greatest amount of feeding when the three sugars were compared at equal concentrations in the same bioassay (3). Disks treated with glucose and fructose were fed upon equally at the three concentrations tested. Sweetclover weevil resistance apparently depends upon a balance between feeding stimulants and feeding deterrents; and the relative contributions of the different factors vary considerably with stage of leaf and plant development (1). Information concerning 1 Contribution from the Nebraska Agricultural Experiment Station, Lincoln, Neb., and the Crops Research Division, ARS, USDA. Supported in part by Crops Research Division and Entomology Research Division, Agric. Res. Serv., USDA Grant No. 12-14-100-8027 (33). Published with the approval of the Director as Paper No. 2687, Journal Series, Nebraska Agr. Exp. Sta. Received Dec. 4, 1969. 2 Formerly Assistant Professor of Agronomy, University of Nebraska (present address, Great Western Sugar Co., Longmont, Colo.); Research Geneticist, Crops Research Division, ARS, USDA; and Bert Rodgers Professor of Agronomy, University of Nebraska, respectively, Lincoln, Neb., 68503. The technical assistance of Patricia Underwood and Henry J. Stevens is gratefully acknowledged. 477 the relative amounts of the three sugars acting as feeding stimulants in sweetclover leaves would aid in determining the role of these sugars in the mechanisms of resistance and susceptibility of Melilotus plants to weevil feeding. Levels of glucose, fructose, and sucrose in resistant and susceptible plants of various ages are reported in this paper. MATERIALS AND METHODS Plantings consisting of 10 plants of M. infesta (Nebraska strain M70) and 10 of M. officinalis 'Goldtop' (F.C. 38,923) were made in a greenhouse at weekly intervals for 13 weeks, to permit comparison of the sugar content of similar leaves of the two species from plants of varying ages. Natural light was supplemented with cool white fluorescent lamps to provide a 16-hr photoperiod. Sampling and extraction of leaves from plants 3 to 14 weeks of age was accomplished in one afternoon, following !i consecutive sunny days. The youngest fully expanded leaf from each of the 10 plants of similar age and specieS was harvested, and these 10 leaves were bulked. One week after the initial harvest, the newly formed youngest fully expanded leaves were similarly harvested and extracted, again after at least five consecutive days of sunshine. For example, the 10 plants of M. infesta from which the first 8-week sample was taken, were used one week later as the source of material for the second 9-week sample. Thus, there were two samples representing each plant age. Following the harvest of leaves from the 10 plants of a group, the three leaflets of each leaf were removed from the p.etiole. Mid-leaflets, used for the determination of dry matter percentage, were weighed before and after drying at 110 C for 6 hours. The 20 side leaflets were weighed, washed with water, dropped into 10 ml boiling water and autoclaved at 120 C for 20 min. Autoclaved extracts were cooled, leaflets were removed and discarded, and the extracts were stored in a freezer for later assay. Additional plantings of both species were made every 3 to 4 weeks, so that several extractions over a period of 3 months could be made on plants of approximately the same age. Ten plants of each species, from 5 to 8 weeks of age, were sampled at each of six harvest dates. All sampling and extraction was done during the afternoons of days having full sunshine. The youngest fully expanded leaf from each plant was harvested individually. Mid-leaflets were used for the determination of dry matter percentage, while the two side leaflets were weighed, dropped into 2 ml boiling water, and autoclaved at 120 C for 20 min. Extracts were stored in a freezer for later assay. In order to remove compounds interfering with the sugar determinations, crude extracts were partially purified by preparative paper chromatography in a manner similar to that described previously (4, 6). Chromatograms were developed with a solvent composed of isopropyl alcohol, ethyl acetate, and water (8:1:3, v/v/v). Glucose, fructose, and sucrose were confined to a single band extending from Rf 0.30 to 0.52; this band was eluted with water. Thin-layer chromatography of the eluates, using the procedure described by Akeson et al. (3), indicated that glucose, fructose, and sucrose were the only sugars present, and that other interfering reducing compounds had been effectively removed. Eluates were assayed for glucose and fructose content by means of a modification of the colorimetric method described by Ting (9). Total reducing sugars were determined by first mixing 1 ml of eluate (representing 1 to 3 mg of dry leaf tissue) with I ml of alkaline ferricyanide solution in an 18 X 150 mm test tube and heating the mixture in a boiling water bath for 10 min. The tube was then cooled in cold water, and 2 ml of 2 N sulfuric acid and 0.8 ml of arsenomolybdate solution were added. Absorbance of the solution was read at 515 nm with a blank consisting of a similarly treated eluate from a chromatogram to which no extract had been applied. Apparent fructose content was determined by the same procedure described for CROP SCIFNCE, VOL 10, SEPTEMBER-OCTOBER 1970 'olal reducing sugars, except that the mixtures of cluate and ferricyanide were incubated at tiC, C [or 30 min, Clu('ose and frucu;se contents were calculated from the total reducing sugars and apparent fructose values by the equation of Ting (~l), A modification of the resorcinol procedure described by Kulka (8) was used to determine sucrose. One ml of cluate was mixed with 3 ml of 30% HCI (containing 0.216 g/Iiter l"eNH4 (S04)" 12 H 20) and 3 ml of O'()5% resorcinol (w/v in absolute ethanol), The mixture was heated at 73 C [or I hour, cooled, and read at 480 nm, The reading obtained provided a measure of total fructose residues (free fructose plus the fructose component of sucrose), Calculation of sucrose content was based on the difference between total fructose residues and the actual fructose content (obtained from the reducing sugar procedure described in the preceding paragraph), , The efficiency of the above procedures was studied III preliminary experiments involving' recovery of glucose, Iructose, and sucrose added to crude extract. Recoveries were 95 to 99% lor glucose, 93 to 94% for fructose, and 98 to 100% for sucrose, RESULTS AND DISCUSSION Average contents of glucose, fructose, sucrose, and total sugars (sum of glucose, fructose, and sucrose) in the youngest fully expanded leaves of iVL mfcsta and J\!I, otticinaZis plants [rom 3 to 14 weeks of age are presented in Fig, 1, Each value in the graph represents the mean of two extracts (one extract from each of the two samples representing each plant age), Triplicate chromatograms of each extract were prepared, developed, and assayed, At all ages, the content of each of the sugars was consistently higher in leaves of J\!I, offirinalis than in corresponding J\!I, infcsta leaves, In AI, officinalis leaves, glucose, fructose, sucrose, and total sugar contents, averaged for all plant ages, were 1.8, lA, 1.9, and 1.7 times as high, respectively, as the averages [or corresponding lV[, infcsta leaves, In addition, the content of each sugar, with the exception of sucrose in J\!I, infesta, tended to increase with increasing plant age, The contents of glucose and fructose were higher in leaves of older lV[, infesta plants than in leaves of young plants of lV[, ottirinalis, The sucrose content of lV[, infest a increased slightly as the young plants grew, remained about the same during the intennediate period of growth, and then decreased rather sharply as the plants matured. The contents of sugars from plants of approximately the same age harvested at six different dates are

Methods of drying forage samples were examined for their influence on the total C, N, and dry matter (DM) content of 'Range? alfalfa (Medicago sative L.). Forage samples were freeze-dried; air-dried in perforated paper bags and on trays; dried in perforated paper bags in mechanical convection ovens at 60, 80, and 100 C; and oven-dried at 100 C for 90 minutes followed by drying at 60 C, or by air-drying. All treatments were terminated after 48 hours. Losses in C and N were measured by changes in C:K and N:K ratios. The DM losses were measured by changes in R. concentration. Carbon and DM were lost more readily than N by either respiratory or thermochemical processes. These losses resulted in an apparent concentration of N in all forage dried between ambient and 100 C. All treatments, when compared to freezedrying, resulted in losses of C and DM. The greatest loss of DM, 5.4% occurred in samples dried at 100 C. Oven-drying at 100 C for 90 minutes followed by airdrying caused DM losses of only 0.2%. Significant differences in actual N content between the various drying methods were not generally observed.

This Paper describes the semi-feral sheep of North Ronaldsay. These sheep are of the Orkney breed, and feed almost entirely on seaweed.Hitherto unpublished material on the numbers of these sheep and on certain biochemical polymorphisms is presented.

Die Auswertung der allgemeinen statistischen Verbrauchszahlen last uber einen Zeitraum von 1935/38 bis 1951/52 gewisse Grundtendenzen der deutschen Ernahrung erkennen. Der Verzehr von Brot und Kartoffeln ist stetig im Abnehmen begriffen. Bei niedrigen Werten fur Gemuse und Obst sowie auch fur Milch ergibt sich somit eine Fett/Eiweis-Kost, deren Haupttrager Fleisch sowie pflanzliche und tierische Fette sind. Auf die ernahrungsphysiologischen Konsequenzen aus dieser Strukturwandlung soll in weiteren Arbeiten eingegangen werden. Structural Changes in the nutrition of the German people from 1935 till 1952 The analysis of the general statistical consumption-figures shows for the period from 1935/48 till 1951/52 certain fundamental tendencies of the German nutrition. Consumption of bread and potatoes is steadily declining. With low figures for vegetables, fruit and milk, a fat/protein dict results, consisting mainly of meat and animal and vegetable fats. The food physiological consequences of this structural change will be dealt with in subsequent papers.

Walleye (Stizostedion vitreum vitreum) eggs were incubated in a temporary jar hatchery using Rainy River water taken below paper mills discharging sulfite, kraft, insulating board, and groundwood wastes. Eggs were also incubated in trays held on and off the bottom in the river below mills, above the mills, and in tributary streams. In two years, survival of eggs in jar controls was 31.2 to 73.5 percent. Survival to hatching of eggs jar-incubated in polluted water was 0.02 to 6.0 percent. At river stations below mills survival of tray eggs on bottom did not exceed 1.2 percent; and off bottom, 3.5 percent. Eggs held on bottom above mills had maximum survival of 37.6 percent; and off bottom, 49.1 percent. In most experiments in polluted Rainy River water the principal cause of mortality was Sphaerotilus growths on the eggs which prevented successful emergence of fry. Prior to hatching, egg-survival rate in jars was similar in controls and in experiments. Chemical treatment to remove slime increased ...

This paper reports on an application of the Markov chain process to an analysis of the size structure of the primary Canadian dairy industry. On the basis of observed changes in the size distribution of “census” farms with milk cows from 1961 to 1966, projections were made of the numbers of these farms by herd size for the years 1971 and 1981. It is projected that by the year 1981 there will be 109,200 farms with milk cows in Canada, a 51 per cent decline from the numbers in 1966. All of the decrease will occur in the smaller size herds of less than 33 cows. Farms with herd sizes larger than this are expected to increase in numbers. Projections were made separately for Ontario and Quebec.

Clutches containing up to five eggs were available from 16 birds over a period of three laying seasons. Variations in egg weight, shell thickness and membrane thickness were studied in relation to the position of the egg within the clutch. It was found that generally the results agreed with those of earlier workers, but the main argument used in the paper is that statistically significant differences are not necessarily a good basis on which to build biological hypotheses when individual clutches and individual birds show a large proportion of results which do not agree with the mean result.

There are numerous environmental variables which directly and independently effect the growth rate of tadpoles. The principal factors are, (1) temperature of the medium, (2) amount of available food, (3) amount of radiant energy through light, (4) amount of surface and available oxygen, (5) amount of accumulated excretory wastes, (6) amount of bacterial growth, (7) amount of available volume per individual, (8) amount of available space per individual, (9) amount of forced or stimulated exercise, (10) presence of growth inhibiting substances, X-substances, or autotoxins. In any experimental work involving tadpole growth rate, all of these variables must either be eliminated or controlled. Of all of the variables listed above, the space factor has not been adequately recognized or evaluated in respect to aquatic forms. According to Allee ('31), Hogg ('54) was the first to note the limiting effect of volume on the growth rate of aquatic forms; Semper ('74, '81) suggested that this retardation of animal growth might be due in part to the mechanical disturbances conditioned by crowding; DeVarigny ('94) suspended glass tubes measuring 2 to 3 cm. in containers of various sizes, the tubes being closed over the bottom with muslin. In each tube he placed a single specimen of Lymnamea stagnalis and concluded from results that the growth variations depend on total volume, surface area, and the accumulation of faeces, rather than space. Crabb ('29) stated that food, foul media, and crowding all effected the growth rate of these pond snails. In respect to the tadpole, with which this paper is concerned. Yung ('85) stated that the dwarfing of tadpoles in crowded conditions was due to insufficient aeration; Bilski ('21) found that frequent changes of water or crowding would retard the growth rate of tadpoles of Bufo and Rania esculenta. A corollary to crowding is an increase in the number of frequency of contacts, and it was to this stimulated exercise that Bilski attributed retardation in growth rate. On the basis of these observations, and those of Semper on snails, Bilski devised the following formula to express growth as inversely proportional to group stimulation (see Allee, '31, p. 115, for derivation)

Approximately 92 per cent. of the growth of the faetus of the rat takes place between the fifteenth day and term, i. e. during the last third of pregnancy. Approximately 54 per cent. of the increase in the weight of the mother during pregnancy occurs after the fifteenth day. The gross increase in weight due to the pregnant condition is 71 grams, which is roughly equivalent to 41 per cent. of the body-weight of the rat. The “permanent” increase in weight during a single pregnancy (no lactation) is considerably in excess of the increase which takes place over the same period in virgin rats. Rats injected with alkaline extract of anterior pituitary gain an excess of 100 per cent. in weight over controls during the first seven days of pregnancy; this increase is retained, and is comparable with that of virgin rats under the same treatment. The author desires to acknowledge the assistance and advice of Drs Wiesner and Robson in the work recorded in this and the preceding paper.

Summary. This paper contains observations on 2612 Rattus rattus from buildings in the port of London, 1519 rats from ships in the docks, both samples obtained during 1941–43, and 1358 rats examined in Cyprus in 1947–48. The sex ratio is considered in relation to the body-weight of the animals, the method by which they were killed and the locality where they were living. The median body-weight at which female rats reach maturity in both England and Cyprus in mid-November to mid-March is approximately 97 g. The corresponding weight for the rest of the year is 87 g. in England and 78 g. in Cyprus. The pregnancy rate is highest in rats on ships and lowest in rats in Cyprus. Seasonal fluctuations in the breeding intensity is most marked in Cyprus where it is high in April and September and lowest in January. On shore in London the year can be divided into two periods, mid-November to mid-March when the breeding rate is declining, and the rest of the year when it is higher; the peak is in September. No obvious seasonal trends in breeding activity are perceptible in rats on ships. The average number of embryos per pregnant female is 7.5 on ships, 6.9 on shore in London and 6.1 in Cyprus. The number of embryos is correlated with the body-weight of the female, being highest in the heavier animals on both ships and shore in London, but not in Cyprus. At least 25 per cent, of the embryos are lost between implantation and full term in rats on shore in London; the figure is probably smaller in rats on ships and in Cyprus. The proportion of the three colour forms of R. rattus in London was similar on shore and on ships in London; this suggests that the shore population is frequently supplemented by immigrants.

The possibility that populations of' small mammals are subdivided into highly isolated demes of small size has been a point of contention in the literature. Much of the evidence supporting this demic structure concept has been accumulated by studies on house mice (Mus musculus) (e.g., Selander, 1970; Anderson, 1964, 1965). Anderson (1970) has used this evidence as support for a model of local population subdivision involving highly complex spatial and temporal structuring, which he suggests is likely to be characteristic of rodent populations in general. This paper is a report of direct evidence of frequent multiple male parentage within single litters in natural populations of deer mice (Peromyscus maniculatus). Thus in these populations the social units (if, in fact, they exist) must be large enough to include two, or probably more, breeding males. This is quite unlike the social structure described by Brown (1969) in Apodernus populations and Selander (1970) in Mus populations, in which one dominant male is thought to do most, if not all, of the breeding.

SUMMARY 1. This paper describes an attempt to find out whether it is possible to test chemical control measures against wireworms by a field techniqpe similar to that used in fertilizer and varietal experimentation. A full account is given of three field experiments using old grassland on a heavy “clay-with-flints” soil. The arrangements and sizes of the plots were as follows: (1) 5 × 5 Latin square, 1/60 acre; (2) 3×10 randomized blocks, & acre; and (3) 6×8 randomized blocks, 1/200 acre. 2. Wireworm populations were ascertained in every case by sampling the soil before and after treatment. The Ladell flotation machine was found rather too small and a modification of the technique using oil drums was adopted. Later, a larger and improved form of the machine was used. In the first experiment six samples (9×9×5 in.) were taken in each plot, making a total of 150 soil sampleswn each occasion. In the second, four samples (9×9×5 in.) per plot were taken. making a total of 120 before treatment, but after treatment the size of the samples was reduced to 6×6 × 5 in., the number of samples remaining as before. In the third experiment two samples (6×6×6 in.) per plot were taken, to talling 96 on each occasion. Local control was introduced in the first two experiments. In addition preliminary experiments were carried out using potatoes and cabbage-leaf as baits as a means of estimating wireworm populations. No relationship was found between the number of wireworms obtained in the baits and the actual number in the soil. 3. The wireworms were grouped according to size in order to ascertain if there was any differential action of the fumigants on the various hetars. No conclusive evidence was obtained. The mean density of the original wireworm population was 65, 335 and 277 per sq. yd. respectively in the three experiments. The uneven distribution of the wireworms in the soil resulted in high sampling errors accounting for most of the experimental error. This aspect of the work is discussed fully by W. G. Cochran in the Appendix. No relation was found between the pH of the soil and the density of the wireworm population. 4. The untreated controls showed changes of -23, +1 and -9% between the first and second sampling respectively. The biggest drop was obtained when the second sampling was done in July and the smallest difference when the second sampling was done in May. It is suggested that the big drop in July might be due to a downward movement of the wireworms to escape the heat, but the evidence is insufficient to prove this point. 5. Fumigants “K” and “S” (mixture of o- and p-dichlorbenzene) reduced the population by 69 and 62 %, but had an adverse effect on the crop (sugar-beet) in both cases, due to insuEcient interval between its application and the drilling of the seed. There was also a residual effect the following year, a reduction in the number of the wireworms and an increase in the plant stand (barley), although there was no sigdicant increase in the final crop yield. 6. Chlorpicrin redilced the population by 46 and 33 %, but there was no harmful effect on the crops (sugar-beet and barley). No residual effect was detected. 7. Fumigant “M” (sodium cyanide) reduced the population by 45 % and increased the yield of the crop (sugar-beet). The residual effect was negligible. 8. Crude naphthalene (“creosote salts”) reduced the population by 60 %, tar + lime by 29 % and ammonium carbonate by 20 %, on summer fallow. 9. Other treatments which all proved ineffective were chlordinitro-benzene, lime alone, and superphosphate.

The present paper dealt with the sequential changes of the distribution pattern of apterous females aphid populations, that were artificially settled at the beginning on the experimental barley ‘field’. The aphids were settled at random or even with a fixed denisty per plant. For five or six days after the settling, the number of individuals followed the negative binomial distributions in all cases while the parametersk andp were varying. The estimated values ofk were rather small for the first one week after the settling, which may suggest that the number of moving aphids between plants was relatively small and the degree of concentration expressing the intrinsic increase was high. After that, as the number of individuals increased, the number of moving aphids between plants would be considered to be increased. It was found that with the lapse of time the degree of concentration decreased ork became larger.

The paper describes experiments and observations on the damage done by mites to stored grain, and methods of assessing the damage. It is confirmed that mites cannot penetrate grains if the grain-coat is intact; but usually less than 10% of the grains are so intact. In laboratory experiments, mites consumed up to 3% by weight of the grain before dying out; they were able to destroy the germ completely, but consumed very little of the remainder; the maximum rate of consumption observed over a 5-week period was 0-29% of grain weight per week; when added to grain at 75% relative humidity in the proportion of 1% by weight, mites consumed 1% of the grain in 27 days at 21d C, or in 37 days at 10-15d C. Although mites consumed the grain more rapidly at higher temperatures or humidities, they survived longer at lower temperatures or humidities, and finally did more damage. Mites consumed wheat germ flakes more rapidly than grain, and finally reduced its weight by 74-85%. A system of symbols to represent degrees of damage to grain by mites, assessed visually, is presented, and approximate values for the equivalent weight losses are given. The relationship between the product, no. of mites per 100 ex. grain × time in weeks, and the degree of damage to grain, was calculated from experimental data; the damage done per unit of this density × time product was 2-2-5 times higher at 25 than at 5-9d C, and about 1-4 times higher at 70 than at 90% relative humidity. The mean density × time value corresponding to 1% loss of grain weight was 526,000 at 250 C, and 1,765,000 at 5-9d C. Data from granary investigations show the degree of damage associated with various levels of population density and grain moisture. In infested storages, the amount of embryo material destroyed ranged from less than 1% of the total (bulk grain) to about 15% (grain in bags). Mites may cause a rise in the temperature or moisture-content of grain, or an increase in the growth of microorganisms; but there is no evidence to suggest that serious damage from these causes is likely except that dense infestations can cause heating.

The mean incubation time in control conditions (saturated blotting paper with pF less than 1.0) was 6.18 days for T. oleracea and 11.0 days for T. paludosa at a temperature of 20°. Fertile T. paludosa eggs increased their weight by just over half between the ages of two and three days. Both fertile and infertile T. oleracea eggs increased weight by about a fifth in the first ten minutes and fertile ones further increased by just over half between the ages of 36 and 48 hours. Eggs on soil of pF values up to 3.6 developed at a similar rate to eggs in control conditions while development at pF 4.2 took longer. The duration of the mid-incubation swelling was not affected by pF up to the value of pF 3.6 but was longer at pF 4.2. The logarithm of the duration of the initial weight increase of T. oleracea varied in direct proportion to pF between values of pF 0.8 and 4.*** ZUSAMMENFASSUNG DIE BEZIEHUNG ZWISCHEN DER WASSERSPANNUNG DES BODENS UND DER ENTWICKLUNGSGESCHWINDIGKEIT DER EIER VON TIPULA OLERACEA UND TIPULA PALUDOSA Eine Methode zur Messung der Entwicklungsgeschwindigkeit der Eier bei 20 ± 5° und einem pF (= log cm Wasserdruck) von < 1,0–4,2 wird beschrieben. Die durchschnittliche Entwicklungsdauer der Eier betrug unter Kontrollbedingungen (auf gesattigtem Loschpapier bei pF < 1,0) 6,18 (T. oleracea) oder 11,0 Tage (T. paludosa). Befruchtete Eier von T. paludosa vermehren im Alter von 2–3 Tagen ihr Gewicht um ungefahr die Halfte. Befruchtete und unbefruchtete Eier von T. oleracea erhohten ihr Gewicht in den ersten 10 Minuten um etwa ein Funftel und befruchtete vergroserten es im Alter von 36–48 Stunden weiter um ungefahr die Halfte. Auf Erde bei pF bis 3,6 entwickeln sich die Eier mit ahnlicher Geschwindigkeit wie unter Kontrollbedingungen. Bei pF 4,2 dauerte die Entwicklung bedeutend langer. Die Dauer der Eischwellung im mittleren Entwicklungsstadium blieb bis zu pF 3,6 gleichfalls unverandert, war aber bei pF 4,2 bedeutend langer. Die Dauer der anfanglichen Gewichtserhohung der Eier von T. oleracea wechselt mit dem pF. Der Logarithmus der Dauer der Initialgewichtszunahme andert sich in direkter Abhangigkeit zum pF zwischen den Werten 0,8 und 4,2.

Water added to a soft wheat, whether as vapour (humid atmosphere) or liquid, was accurately assessed by the oven method (heating 4 h. at 113°), but water added to a hard wheat by either method was over-assessed proportionately to the amount added. The over-assessment amounted to 1% when the moisture content was increased from 9% to 25%, on the dry weight basis. The amount of water removed from both varieties of wheat by drying in a warm air current was over-assessed. That from the hard wheat was over-assessed proportionately to the amount removed (but only to the extent of about 0.25% on drying from 25% to 9% on the dry weight basis), whilst the over-assessment was inversely proportional in the case of the soft wheat. It is concluded generally that the ability of an oven-drying method to measure known quantities of water in wheat is related to the type of wheat. This is consistent with results obtained in the first paper in this series.

Experiments in the mass culture of Phneodactylum using 15-L cultures, with inorganic fertilizers or sewage effluent as a nutrient source, are described. Following inoculation, growth may start immediately or after a short lag. A logarithmic growth phase is followed by a period of constant population density or by an immediate decline. Growth rate in the logarithmic phase varied from 0.25 division/day in winter to >l division/day in summer. Purified sewage effluent, with or without salinity adjustment, is at least as good as inorganic fertilizers as a source of nutrients for the growth of PhaeoductyZum. INTRODUCTION purified sewage effluent reduced the saSome of the problems encountered in linity of the culture in the jars to which it the mass culture of marine plankton algae was added, the salinity in some cases was (Ansell, et al. 1963) cannot be investigated adjusted by the addition of a mixture of easily in large tank cultures, partly because NaCl, MgCla, NazSOJ, CaClz, KCl, and of the difficulty in controlling environmenNaIICOR in the proportions recommended tal conditions sufficiently accurately, and by Harvey ( 1955) for the preparation of partly because the setting up of a largeartificial sea water. Additions of sewage scale tank culture is a time-consuming opeffluent were made to give as near as poseration. Investigation of some problems sible 0.8 mg P/L. h as therefore been carried out using Cell counts, determinations of inorganic smaller scale outdoor cultures, and this panitrogen and phosphorus fractions in the per outlines the work carried out in this medium, and chlorophyll content determiway. nations were carried out by the methods described in part II of the present series MATERIAL AND METHODS of papers (Ansell, et al. 1963). The experiments were conducted using We gratefully acknowledge the co-oper15 L of culture in battery jars of 20-L total ation received from Mr C. L. Bennett, capacity, which were placed on the roof of Superintendent of Broadstone Sewage PuPoole Electricity Generating Station, As in rification Works* previous series (Raymont and Adams 1958; Ansell, et al. 1963), flue gas from the staRESULTS tion boilers, or “pure” carbon dioxide from The general conditions prevailing in the cylinders was used to reduce the pH as series of experiments to be described are required. No attempts were made to conshown in Table 1. Series xiv-xvi, xviii, xxi, trol conditions of temperature and light and xxixa used normal nutrient additions; which therefore showed their usual diurnal and seasonal rhythms. in series xxviii, xxx, xxxii, and xxxiv puriNutrient additions were usually designed fied sewage effluent provided the source to give 0.8 mg P/L and 6.0 mg N/L (25.8 of nutrients, except in control jars where the normal nutrients were used. pg-at. P/L and 428.5 pg-at. N/L), using The results in general confirm earlier ammonium sulphate and disodium hydrogen phosphate as fertilizers. In experiments observations made on the growth of Phaeodactyluna in outdoor battery jar cultures where purified sewage effluent was used as ( Raymont and Adams 1958). The rates nutrient source, the effluent was collected of growth obtained are summarized in Tafrom Broadstone Sewage works. Since such ble 2.

How little we realize the complexities attendant upon the lives of wild animals until we have undertaken to investigate and reveal them. So it was in connection with the gathering of material for this paper, when observations were undertaken to determine the active life movements of the Columbian ground squirrel (Citellus columbianus columbianus) in regard to seasonal and daily activities, aside from its normal periods of aestivation and hibernation. To gain the information recorded here, field observations were made, supplemented by studies of the animals in the very liberal confinement provided for those under control and study (Shaw, '25a). Binoculars were used for more certain identification in the field, while temperatures were taken in degrees Fahrenheit. The elevation at Pullman is 2536 feet at the Campus of the State College of Washington. The hours of each day of observation were continuous throughout as to time and made by one person, the writer. The time involved extended across four years, 1910 to 1914, with the chief investigations of these problems pursued in 1910 and 1911. For the sake of economy and brevity, wherever the term "squirrel" is used through the text, it will be understood to refer to the Columbian ground squirrel. In studying the activities of this squirrel and to some extent its related forms, it was necessary to regard them especially from two view points, seasonal and daily. Such investigations showed that these movements were subject to and modified by many influences such as season, sun, wind, rain and snow, drought, slope of the land and altitude. It was also noticed that the species was influenced both seasonally and daily by such complexities as the warmth and brightness of the sun's rays and their ability to reach all parts of the earth's surface equally; bringing the animals from their winter nests later in spring on the north slopes of hilly territory, where the snow remains piled deep and also later of a morning, on a sunless slope (Shaw, '25c). Of course the action of the sun on the vegetation and the relation of the animal to surounding food so produced, is of intimate association (Dice, '19, pp. 17-18).

Considerably more carotene was lost from the middle of a commercial type stack of dry lucerne meal than from the edges. The percentage loss, small near the outermost edges of paper sacks which were exposed to air, rose sharply in the first few cm. and then more gradually to the centre of the stack. Part of the increased loss in the centre was due to the higher temperature there. The major part of the difference in the rates of loss was due to the protective effect of moisture taken up from the air at the outer surfaces of the stack. These conclusions were verified by isolating sections of stacks of dry meal in tubes 21/2 metres long closed at one end and so stored as to eliminate temperature gradients. Loss of carotene was high within a tube except near the exposed end where moisture had been taken up.

Summary. It is a well established fact that the body temperature increases during muscular exercise, and that the increase is regulated (NIELSEN, 1938). It was the purpose of this paper to study the effect of the increased body temperature on the performance of maximum work, viz. a work performance of short duration (12 to 15 seconds) and a work performance lasting 4 to 5 minutes. The effect on a peak effort (a “push” or a “pull”) was also studied. The experiments showed: 1) A given amount of work could be performed better – i. e. in a shorter time – when the organism was warmed up by a preliminary work. Also a greater muscular tension could be developed when “warmed up” than when not. 2) A passive warming up – e. g. by means of radio diathermy or by hot baths – also increased the capacity for work. 3) Massage had no beneficial effect on the performance. 4) The harder the preliminary work was, the higher rose the temperature and the better was the performance (only demonstrated in the work of shorter duration (12 to 15 sec.)). 5) The increased ability to perform hard work is closely correlated to the temperature of the working muscles. 6) The maximum oxygen uptake is slightly higher when the organism is warmed up than when this is not the case, but the oxygen necessary for a certain amount of work is reduced. From these results it is concluded that a higher temperature in the muscles benefits the ability to perform work by accelerating the chemical processes in the muscles, probably also by decreasing the intramuscular viscous resistance. The accurately regulated higher rectal temperature in work (NIELSEN) allows the muscles to obtain a higher temperature during work than would otherwise be possible.

IN previous papers (1935, 1939, 1940) the author has shown that slight mechanical deformation of the cells of the lamina of starved foliage leaves greatly stimulates their oxidative respiration rate, and that a period of 2-3 days is required for their recovery from the stimulated condition. Successive stimulations described in these experiments were carried out after intervals of time sufficient for the normal starvation drift of respiration of the leaf sample to be reattained. From these experiments no measurements were obtained of the sensitivity of the leaf to stimulation during the recovery period. In order, therefore, to discover to what extent sensitivity persists during this period, and to investigate any possible fatigue effects of continued stimulation, experiments were carried out at relatively short time intervals. Two distinct types of experiment were performed with detached leaves of cherry laurel at 22-50 C. In one the leaf sample was subjected to two successive stimulations only, the second taking place at varying intervals during the recovery period from the first stimulation. From the second effects, measures of the sensitivity of the leaf to stimulation during this period could be obtained. In the second type of experiment a series of consecutive stimulations at short time intervals was performed. In this way the development of fatigue phenomena was investigated.

The paper presents effects of phosphorus deficiency and seasonal variations on nitrogen and carbohydrate metabolism of Japanese mint (Mentha arvensis L. var. piperascens, Holmes). Mint plants were grown in sand cultures under full nutrition and under phosphorus deficiency conditions during winter and summer. Various nitrogen and sugar fractions were determined in the component parts at specified periods of growth stages. Phosphorus deficiency disturbed the nitrogen metabolism at the stages for amide and amino acid formation, which resulted in an accumulation of carbohydrates. The content of total soluble and total nitrogen was higher and that of insoluble nitrogen was lower in summer as compared with winter plants. Of the soluble fractions, the ammonia, amide and nitrate nitrogen were higher and the ‘rest’ nitrogen lower in winter plants. Nitrate formed the highest bulk of the pool of soluble nitrogen in winter, whereas in summer ‘rest’ nitrogen was most abundant. The content of total sugar in winter plants far exceeded that of summer plants, which was wholly due to increase in sucrose content. Glucose was the predominant reducing sugar in both seasons. However, the summer plants were richer in glucose than those from the winter.

In liquid inorganic axenic cultures of Chlorococcum echinozygotum containing 20 ppm CaC12, which was optimal for growth, motile cells were released in abundance; gametic fusion occurred commonly and the resulting zygospores reached a maximum of 31% of the total cell population. In a Sr-replacement medium, less growth, not quite equivalent to that with 5 ppm CaCl2, occurred, and more than 99% of the cells were non-motile vegetative cells. Old Sr-replacement cultures contained much-enlarged vegetative cells which, upon transfer to fresh Sr-medium, produced entrapped motile cells equivalent in number to those produced and released upon transfer to fresh Ca-medium. Release of these entrapped cells, after their production in Sr, was induced in 4 hr by transferring them to Ca (25 ppm CaCl2). PREVIOUS studies with Protosiphon botryoides Klebs (O'Kelley and Herndon, 1961; O'Kelley and Deason, 1962) demonstrated that a deficiency of Ca, NO3 or S04 ions caused a decrease in production of free-swimming zoospores. Techniques used in these studies did not separate the processes of protoplasmic cleavage and zoosporogenesis from zoospore release. However, observations indicated Ca as a major ion influencing zoospore release, while NO3 and S04 appeared to affect mainly protoplasmic cleavage and zoosporogenesis. With Chlorococcum echinozygotum Starr, another organism that can utilize Sr in place of Ca, at least in part, it is possible by procedures described herein to separate the processes involved in motile cell production from motile cell release. Thus, Ca and other ion effects on release can be studied, uncomplicated by the effects of these ions on motile cell formation. This paper describes the results obtained with C. echinozygotum using these procedures. MATERIALS AND METHODS-The cultural strain of Chlorococcum echinozygotum used in this investigation was No. 118 from the Indiana University Culture Collection of Algae (Starr, 1960). The basal medium containing Ca was that of Deason and Bold (1960), except that in the growth studies it was modified by lowering the CaC12 level to 20 mg/liter; Hancock (1960) determined this concentration optimal for the growth of this organism. Other media contained a Sr replacement for Ca, or a Na replacement. Stock cultures were maintained in Pyrex test 1 Received for publication March 4, 1964. 2 Present address: Mineral Nutrition Laboratory, Soil and Water Conservation Research Division, Agricultural Research Service, USDA, Beltsville, Maryland. This study was supported in part by research granit AM 03680-04A1 from the National Institute of Arthritis and Metabolic Diseases, Ptublic Health Service. tubes as slants containing basal nmedium and agar. From these stock cultures aseptic transfers of cells were made to 500-ml Pyrex Erlenmeyer flasks containing 200 ml of either Caor Srmedium. These cultures were placed under 300 ft-c illumination on a 12-hr dark-12-hr light cycle at a temperature of 21-23 C. After the cultures had reached the maximum stationary phase of growth, inoculations were made to experimental media and vessels. These experimental cultures were subject to the same conditions of light and temperature as the stock cultures. Some experimental cells were maintained in hanging-drop preparations under similar environmental conditions. For the growth measurements in Ca and in Sr, inoculations were made to experimental vessels so that the initial optical density was 0.02, as determined by a Colenman Jr. Spectrophotometer at 400 my. Method for determining production and release of motile cells-Cultures used to supply cells to be immersed in fresh media were in the maximum stationary phase of growth, i.e., the value of the velocity coefficient of the rate of growth was zero. Just before the dark period, the cells were centrifuged, the old culture medium decanted, and the cells washed twice in the experimental medium to be employed. The cells were theni placed in a small Petri dish and covered to prevent entrance of light. At the beginning of the light period, the following morning the dish was uncoveied and allowed to remain undisturbed until maxirnal zoospore production was reached-i.e., in about 2-3 hr. The cells were stirred vigorously to insure thorough mixing and were then pipetted to a haemacytometer. Motile cells which were swimming freely in the medium were counted and expressed as pereentages of total cells. Total counts involved about 200 cells. Counts were analyzed by the t-test for significant differences between mean values (Lacey. 19.533).

A study of COS-removal during July and August, 1954, under natural conditions in western Lake Erie demonstrated a maximal rate during the hours of 0700-1000 (10 rmoles CO2 absorbed per liter of water per hour), a reduced rate during the hours 1000-1600 (Gpmol/L/ hr), a slightly negative rate during the daylight hours 1600-1900 (1 pmol/L/hr), and nighttime negative rates similar to the day-time positive rates (-6pmol/L/hr). Doty and Oguri (1957) have reported evidence of daily periodicity in photosynthetic rates exhibited by marine phytoplankton. They demonstrated a 5.7-fold higher rate for collections taken at 0800 than for collections taken at 1900, and showed that a sharp decline in photosynthetic capacity was evident during the late daylight hours 16002000. In my report on photosynthesis of phytoplankton in western Lake Erie (Verduin 1956a) I described a method of measuring photosynthesis under completely natural conditions. This is accomplished by measuring the pH of water samples collected at intervals during the day, using a Beckman pII meter, The pH change between any two intervals can then be converted to CO2 change by referring to a curve prepared by differential titration of the lake water with O.OlN NaOH. During July and August, 1954, surface water pII values were determined at 3-hour intervals with the exception of the 2200-0700 interval, during which no determinations were made. These determinations were not planned to study periodicity in photosynthesis, but simply to measure the magnitude of CO2 changes under completely natural conditions. After reading the paper by Doty and Oguri I recognized that our data contained an interesting trend which might represent the effect of this phenomenon. The observed pH changes during each time interval (Eastern Standard time) were converted to pmoles COz absorbed per liter of water per hour and are shown in Figure 1. A wide scatter of values is evident (caused by variations in plankton population, meteorologic conditions, etc.) including some negative values during the hours of 1000-1600. These were associated with dense cloud cover and rain during the interval between pH determinations. The data show a maximal rate of CO2 removal during the 0700-1000 interval. The mean value for that interval is about 10 pmoles of CO, removed per liter of water per hour. The photosynthetic rates were lower during the 1000-1300 and 1300-1600 intervals, yielding a mean of about 6, if the negative values are excluded. During the 1600-1900 interval negative values were observed more often than positive values, and the mean rate computed from the data is about 1, indicating that the respiration rate in the aquatic community during these hours usually exceeded the photosynthesis of the autotrophic component, although the mean light supplies during this time interval (submarine photometer data, Weston photronic cell) were about one-third the mean intensity during the 0700-1000 interval. On the basis of photosynthesis vs. light intensity curves (Verduin 1956a) a rate about one-half as high as the 0700-1000 rate would be expected, rather than the negative average rate appearing in Figure 1. During the hours of darkness negative values were observed, indicating a mean respiration rate of about G pmoles of COz evolved per liter per hour. The low rates of photosynthesis observed during the late afternoon are similar to the decline in activity observed by Doty and Oguri in samples collected during this time of day. Their methods were quite different

THE IMPORTANCE of the unicellular green alga, Chlorella vulgaris, to plant physiologists engaged in studies of cellular metabolism and especially of photosynthesis is well known. Relatively few detailed studies have been made of its growth, however. The present paper deals with the growth curve of Chlorella in cultures inoculated with different numbers of cells taken from parent cultures of the same age. Multiplication, or increase in cell number, was used as an index of growth in this work, although it is realized that a period of cell enlargement precedes each division, and that growth is the result of these two processes. MATERIALS AND METHODS.-Cells for the experiments were withdrawn from four-day-old, rapidly growing stock suspensions of Chlorella vulgaris cultured asg previously described (Craig and Trelease, 1937; Pratt and Trelease, 1938) in a solution that contained KNO3, 0.025M; MgSO4 7H20, 0.02M; KH2PO4, 0.018M; FeSO4 7H20, 0.00001M; potassium citrate, 0.00001M; and Zn, Cu, B, and Mn in approximately the concentrations employed by Trelease and Trelease (1935). The initial pH of this solution was 4.45. New stock cultures were started daily so that there was always available a supply of cells of approximately the same physiological age and activity. Cells were separated from the culture medium and were washed in three changes of distilled water by repeated centrifugation and decantation. They were then suspended in distilled water and the density of the population in the suspension was estimated from haemacytometer counts. Inocula containing the desired number of cells were pipetted into 500 ml. Pyrex glass Florence flasks, each of which contained 150 ml. of the standard nutrient solution. The flasks were continuously illuminated from below by a water-cooled battery of twentyfour 50-watt frosted Mazda lamps. The light intensity, measured by means of a Weston photoelectric-cell light meter, Model 603, varied from 21,000 lux to 18,000 lux. The lamps were replaced by a complete new set when the intensity fell below this value. The temperature at the level of the flasks varied from 18? to 220C. A gas mixture containing 5 per cent CO2 and 95 per cent air was bubbled continuously through the solutions. The cultures were shaken vigorously twice daily to insure separation and uniform suspension of the cells. Growth measurements were made periodically by withdrawing small samples from each flask and estimating the cell population from haemacytometer counts. Triplicates of each culture were prepared, 1 Received for publication November 27, 1939. The author is indebted to Miss Jane Fong for valuable assistance in the laboratory. and cell counts were based on the averages of haemacytometer counts of four different samples from each flask. Each point in the figures represents, therefore, the average of twelve samples. The maximum deviation from the mean value occurred in the lower portions of the growth curves and never exceeded 5 per cent. Over the major portion of the curves in all cultures the deviation of individual cultures from the mean value was less than 3 per cent. EXPERIMENTS AND RESULTS.-Figure 1 shows the growth in cultures inoculated with different numbers of cells withdrawn from parent cultures of the same age. Since the points describe sigmoid curves, it seemed of interest to examine the data to ascertain whether they could be represented by the equation characteristic of autocatalyzed monomolecular reactions that has been found, in many cases, to describe reasonably well the growth of populations and of individual organisms (Ostwald, 1908; Robertson, 1908a, 1908b, 1923; Reed and Holland, 1919; Reed, 1920, 1921a, 1921b, 1928a, 1928b, 1932; Gaines and Nevens, 1925; Porterfield, 1928; Pratt, 1936). The differential form of this equation expresses the rate of growth, and may be written

The duration of the subdivisions of the nuclear cycle in cells from the root tips of Tradescantia paludosa was determined by the labelled mitosis method. These times were found not to increase or decrease in direct proportion to each other at the three temperatures tested, 13, 21 and 30 C. The main difference between the nuclear cycles at 30 and 21 C was in the shortening of the pre-DNA synthetic period (G1) at the higher temperature. A comparison between the nuclear cycle at 21 and 13 C showed that at the lower temperature mitosis and the post-DNA synthetic period (G2) were approximately tripled in duration while DNA synthesis was doubled. Cell synchronization and radiosensitivity are discussed in relation to these findings. THE EFFECT of the environment on the girowth of cell populations has long been of interest and numerous studies have been performed in attempts to determine changes that may occur in populations grown at different environmental means. A factor that changes almost continuously under natural conditions is the temperature, and it is without doubt one of the major items that influences the rates at which cell populations grow (Brown, 1951; Evans and Savage, 1959; Hughes, 1952). This paper is devoted to a description of the growth of cells in root tips of Tradescantia paludosa at three different temperatures. The popuilation is analyzed by using the labelled-mitosis technique (Wimber, 1960) with tritiated thymidine and is subdivided with respect to the duration of the DNA synthetic period and mitosis. It is shown that the durations of the various subdivisions of the nuclear cycle are bDy no means uniformly lengthened or shortened by temperature changes, but some parts are altered much more profoundlv than others. MIATERIALS AND MIETHOI)S-Root tips of Tradescantia, paludosa were used as experimental material. Plantlets were removed from the clonal parent (B2-2, A. H. Sparrow's clone) and the bases placed in aerated Hoagland's solution. They were given constant light (ca. 500 ft-c) and constant temperature. Three temperatures were used, 13, 21 and 30 C. Well-developed roots were usually present within a week. Nuclei in the root meristems were labelled by growing the rooted plants in an aerated nutrient solution containing 0.5 ,c/ml H3-thymidine (New England Nuclear, 3.6 c/mmole) for 30 min .The roots were washed thoroughly in water following label' Received for publication February 15, 1965. Part of this study was carried out at Brookhaven National Laboratory under the auspices of the U. S. Atomic Energy Commission, and part was supported by Public Health Service Research Grant GM 11702-01 from the National Institute of General Medica.l Sciences. The technical assistance of Miss Mary Winnike is gratefully acknowledged. ling and placed in a nutrient solution for further growth. Root tips were collected at various intervals after labelling and fixed in acetic-alcohol (1:3); they were hydrolyzed for 10 min in N HCI at 60 C and stained by the Feulgen method. The root cap was removed and squashes of the intensely stained terminal portion of the root tip were prepared on slides; the cover glasses were removed by the method of Conger and Fairchild (1953). Autoradiographs were made using Kodak NTB liquid emulsion. Exposure was for approximately 3 months. The percentage of mitotic cells labelled was determined by using samples of 100 prophase cells from each slide. Eight roots were sampled at each time interval. Ratios of labelled cells to cells in mitosis were also determined in some cases, and with these a total of 1000 cells were scored on each slide. The labelled-mitosis technique is the method utilized here (Quastler and Sherman 1959; Wimber, 1960, 1963; Evans and Scott, 1964) for the determination of the nuclear cycle and its various subdivisions as they relate to DNA synthesis. The nuclear cycle (C) for this type of analysis may be divided into mitosis (M), DNA synthesis (S), pre-DNA synthesis (G1) and post-DNA synthesis (G2). A discussion of this method is given in the above references and need not be repeated here. Suffice it to say that the duration of the subdivisions of the cycle may be estimated from a labelled prophase (P) curve. An example is given in Fig. 1, and estimates of the durations of G2 + P/2, S and C may be read directly from the figure as distances on the abscissa, using as end points the positions at which the rising and descending curves cross the 50% mark. The duration of GI + mitosis P/2 may be calculated by subtraction of G2 + P/2 + S from C. The duration of mitotic stages may be estimated by observing the frequency of labelled cells and mitotic figures in root tips fixed immediately after a 30-min labelling period. In an asynchronous

In former papers by R. H. True and H. H. Bartlett (I, 2) there was found to be a point in the absorption curve for the lupine grown in various salt solutions, at which the absorption and excretion of electrolytes were in equilibrium. For the lupine this value was found to be about i6 x io-0 normal expressed as NaCl. The conditions which exist at this point have been further studied in the squash, peanut, and soy bean. The values have been found to differ slightly for the various plants used. The absorption minimum for the same plant seems to have nearly the same value independent of the volume of the solution, the concentration of the salt, or the kind of nutrient salt used. The quantity of salt solution offered must, of course, be within the requirements of the plant during its growth period, so that the minimum may be reached, and the concentration must be below the toxic limit. The constancy of the equilibrium concentration when once attained is shown by the graph for sweet corn in calcium nitrate (fig. i). The value of i2-i5n x io-0 Ca(NO3)2 was held for 24 days by five cultures in this series. In cultures of this plant grown in KNO3 and Mg (NO3)2, practically the same value was obtained. The graph for the absorption of the squash in Ca(NO3)2 (fig. 2) gives the average values for twelve cultures at each concentration indicated. The squash seems unable to maintain a concentration as low as corn, giving a value of 35-40n x io-I Ca(NO3)2 as its absorption minimum. The peanut is able to maintain a concentration of 5on x Io6; the soy bean one of about 20n X IO-6 expressed as Ca(NO3)2. Sweet corn gave a more nearly constant value than the other plants tested. The specific minimum concentration for absorption is controlled by at least two classes of factors. One external factor, the concentration of CO2 in the air and in the solution saturated with it at the given temperature, like other similar purely external factors, must be the same for different plants growing under the same conditions.

Five test shipments were conducted involving 98,000 lb of beef quarters and primal cuts transported 270–1350 mi and requiring from 19–120 hr intransit. Trailer temperatures were affected by loading patterns, product densities, positions of palletized product or paper partitions, thermostat settings and air conveyance systems and correspondingly, the temperature conditions observed were generally inadequate for maintenance of beef quality. The use of polyethylene bags or poly vinyl chloride film significantly (P < .05) reduced intransit shrinkage as compared to unprotected cuts in 7 of 16 comparisons. Considerations of costs for materials, package application and removal and the monetary value of reduced weight loss suggest that the concept is economically feasible from the standpoint of savings in weight loss alone. Beef protected by polyethylene or polyvinyl chloride exhibited more desirable lean color and subcutaneous fat cover scores at shipment destination in comparison to beef which was unprotected during transit. Although bacterial counts did not generally differ among treatments, the surfaces of cuts protected by plastic materials were more moist than corresponding surfaces on unprotected cuts. Since increased moisture is conducive to enhanced microbial growth, prolonged storage in the plastic packaging materials should be avoided. No compensatory weight loss was observed during subsequent cooler storage after protective packaging materials were removed.

Summary. In the present paper we report on an investigation in which the amount of hemoglobin determined after the method of SJOSTRAND (1948) in a number of athletically trained men and women has been compared with that in an average group of the respective sexes. The athletically trained men and women showed considerably higher amounts of hemoglobin and blood volumes than the average material. On the whole, the best trained men deviated by 41%, and the women by 44% from the reference material. In three men and one woman the amount of hemoglobin was determined just before and immediately after a skiing tour in the mountains. The figures were 10–19 per cent higher after the training than before. In a patient who had been confined to bed for a considerable length of time (owing to fracture of the leg) the amount of hemoglobin was determined repeatedly. It showed a successive decrease, amounting at its maximum to 15 per cent of. the original figure. The amount of hemoglobin and blood volume seems accordingly to vary with the degree of physical training. The costs of the investigation have in part been defrayed by a grant from the Therese and Johan Andersson Memorial Fund.

Rates of oxygen consumption were determined for: 1) single young-of-the-year white bass, Morone chrysops (Rafinesque), forced to swim in a rotating annular respirometer, and 2) groups of young-of-the-year fish fed meals of live zooplankton. Sustained swimming activity and maximum metabolic rates generally occurred at a rotation velocity of 15 rpm. The decline in oxygen consumption with time and increased velocities in six experiments suggested decreases in excitement and swimming activity. Post-feeding increases in oxygen consumption were observed in six groups. After this initial elevation, metabolic rates continued to increase slightly or declined. The importance of measuring the components of total respiration and their caloric equivalents is stated and will be discussed in a subsequent paper.

Important advances have recently been made in the evaluation of freshwater resources. The planktonts, bottom animals, and plants have been counted, weighed, and analyzed. The rate of propagation and dissolution of the organisms in fresh-water is being studied and some information concerning the rate of " overturn " is thus obtained. It will not be possible to estimate, in a scientific way, the number of animals that each type of environment is capable of supporting until the rate at which each species is consuming materials from the various food resources is known. The present paper relates to one phase of this general problem-describing experiments in which the volume and weight of food consumed per day was determined for four types of fishes: largemouth black bass, pumpkinseed, rock bass, and two species of bullheads. Some observations were also made on long-nosed gars. The fishes used during the experiments, except the gars, were kept in large fruit jars from which the bottoms had been removed. These had a capacity of about i,900 cc. Each end of the jar was covered by a piece of clean cheesecloth held in place by a strong rubber band. The jars were in a covered, metal trough through which water ran continually, and their long axes were parallel to the current so that water ran through them. The watersupply was that of the city of Madison. The temperature of the water varied from I8.70 C. to I9.60 C. The gars would not eat when kept in small wire cages and were fed in a compartment of a covered metal trough which measured i65 cm. long, by 45 cm. wide, and in which flowing water was 20 cm. in depth. At the beginning of each experiment a fresh supply of fishes was secured from Lake Mendota, and all were kept for one day without food before being tested. The length, volume, and weight of each individual was deter-mined before it was placed in a jar. Ten individuals of each species were tested at the same time. During the experiments the food was changed daily, except that it was usually left in the jars over Sunday. A fish was supplied with more of one kind of food than it would be likley to consume during twenty-four hours. Next day a new food was supplied and allowed to remain for about twenty-two hours. Before being placed in a jar with a fish

The concentrations of the isoflavones biochanin A, genistein, formononetin, pratensein and daidzein in leaves of four varieties of red clover and two of subterranean clover have been measured by a paper chromatographic-spectrophotometric method. Biochanin A and formononetin are the predominant isoflavones in red clovers whereas biochanin A and genistein are the most abundant in subterranean clovers. For both species the isoflavone levels differed between varieties and between sampling dates. Higher levels were found during flowering for red clovers and before flowering for subterranean clovers. The isoflavone contents have been calculated to have oestrogenic activity equivalent to 2–17 μg. of stilboestrol (% dry wt.) for the red clover samples and 22–48 μg. of stilboestrol (% dry wt.) for the subterranean clover samples. The potency of some of these samples is much higher than potencies previously reported in the literature.

Purpose.-The backround of all ecological work dealing with fluctuations in animal numbers and resulting population changes is laid in the analysis of environmental factors producing such fluctuations. Most of these factors are not simple, but rather are of a complex nature, representing the interaction of such variables as temperature, humidity, light, evaporation, etc. to produce greater or lesser fecundity, resistance to disease and to competition, and in some cases greater or lesser velocity of growth or development at a critical period in the life history, all of which influence population. Of the physico-chemical components of the environment, radiation within the range of wave lengths referred to ordinarily as light has received relatively little attention. The evidence which has been offered in many cases was gathered incidentally to other research. Most of the literature dealing with the problem of the effect of radiant energy of the visible spectrum upon rate of development or rate of growth was done previous to 1900 and suffers from the lack of adequately measured and controlled laboratory techniques. Recent work on radiation has been largely with the wave lengths above 700 my or below 320 mg. In the analysis of natural conditions the latter radiation plays a relatively small part. Beginning in 1934 and on the basis of preliminary work done in 1932 and 1933 on Physa gyrina the experiments covered in this paper were designed to determine: 1. The relationship of temperature to velocity of growth in Ilelisoma trivolvis pseudotrivolvis (F. C. Baker), considering only the period from fertilization to hatching of the egg; 2. What effect upon the temperaturevelocity curve, if any, could be observed when the embryos developed under the light passing through various filters; 3. The oxygen consumption of the eggs during the developmental period, and, 4. Some of the relationships between light, temperature and oxygen consumption. Literature.-Beginning with Edwards (1824) who claimed that tadpoles showed no development in the dark, and continuing through the work of Rugh ('35) who found no effect of wave length of light on development of frog tadpoles, the literature on the subject has contained almost every possible viewpoint on light-growth or light-development relationships. As Rugh and others have pointed out, probably most of the inconsistency is due to lack of control of other variables and the failure to distinguish between luminous intensity and radiation. Higginbottom (1850, 1863) found no differences in growth rates of tadpoles raised in light and dark. Beclard (1858) working with the larvae of Musca carinaria, reported that larvae grown in violet light, grew to be three times the size of those grown in green light. The sequence of colored lights, producing larvae in order of size from large to small, was violet, blue, red, yellow, and green. MacDonnell (1859) found no differences in the size of tadpoles raised in darkness and in light. Schnetzler (1874) reported a slight retardation of growth in darkness. He I Thesis submitted for the Doctorate at the University of Illinois, 1937.

Milk is a nearly complete food, furnishing proteins of high quality, essential minerals in easily assimilable form, and several of the vitamins as well as other nutrients. It is widely accepted that unless there are specific contraindications, the diet of young persons should contain liberal daily allowances of milk (30). At present a large part of the population of the United States is consuming less milk than is generally regarded as adequate for optimum growth and vigorous health (29). Among families whose food expenditures are moderate or liberal, the problem of adequate milk consumption is largely an educational one. In low income groups, in which the money expended for food is greatly restricted, improvement of the diet through the extension and increase of milk consumption, while still dependent upon intelligent food selection, is more closely related to the availability of inexpensive forms of milk. Dry skim milk affords a number of economies which greatly reduce the cost of milk solids other than fat to the consumer. The use of dry skim milk in the diet increases the mineral and vitamin intakes with relatively small addition to the food expenses. Although dry skim milk contains practically none of the fat of whole milk, and its vitamins A, C, and D contents are negligible, it provides, unimpaired, the solids other than fat of fresh milk as well as vitamin B and riboflavin (vitamin G). The transportation and delivery costs of milk solids in the form of dry skim milk are significantly less than those of milk in the fluid form as practically all of the water has been removed. The product can be stored unrefrigerated for considerable periods of time without deterioration. Experiments in the Bureau of Dairy Industry have shown that inexpensive packaging in laminated-glassine-lined paper bags gives adequate protection for 5 weeks when kept at 730F. in an atmosphere having a relative humidity of from 85 to 95 per cent. In such a container, or similarly protected, dry skim milk can be stored in the home without refrigeration. Dry skim milk has been widely used industrially in bread making and in the manufacture of candy, confectionery and ice cream. Brands tested by the United States Public Health Service have been found to yield a reconstructed milk, which, under a pediatrician's supervision, can be used as a safe and satisfactory substitute for fluid milk in infant feeding (5, 27). Roberts, Carlson, and MacNair, in a study of institutional diets, reported significant improvement in the quality of the diets, through dry skim milk supplements to the customary fluid milk supply of the institution (17). With small addition to the food expense the calcium and phosphorus intakes of nursery school children were increased by the use of dry skim milk in cooking and as added solids in milk served as a beverage (12). Supplements of 2 to 4 ounces per person per day of dry skim milk have been found "to reduce greatly the incidence of pellagra among families which, in times of stress, subsist on a very monotonous and one-sided diet, containing very little

SUMMARY This paper has presented certain demographic data of forty populations of house mice from English grain ricks. The populations are grouped into four density classes on the basis of the number of weaned mice per cubic metre. The resulting demographic averages of various density classes are then compared. Relatively little reproductive alteration occurred in rick populations in relation to density. The major “density effects ” so often observed in laboratory studies did not appear or were only moderately expressed in these data. Mortality rates of the populations revealed no dramatic or conspicuous change throughout the density classes studied (as evidenced by weight ratios and sex ratios). Fecundity of both sexes remained high throughout all density classes. Fertility revealed a significant decline in the highest density class, but it still remained at high levels. Pregnancy rates declined from 58 per cent in the low density class to 43 per cent in the very high density class. Average litter size fell from 6·23 to 5·11. Embryonic and fetal resorption increased significantly in the highest density class (14 per cent and 27 per cent). The general rate of reproductive increase declined with increasing density. The incidence of wounded males increased significantly in the highest density class (0·8 per cent to 21·1 per cent). Adrenal weights did not reveal adrenal hypertrophy in crowded populations. The relative stability of rick populations with increasing density is probably a reflection of the high quality of the habitat. Density effects are undoubtedly minimized by the favourable abundance and distribution of food and cover. It is of equal interest that individual populations in this relatively uniform habitat did show wide variations in their population size and structure. The fact that this variation is not obviously related to density, food, or cover, focuses attention on factors outside the normal realm of physical habitat as major population influences.

In the course of a study of Indian lotus fruits (2), I had occasion to investigate the rate of water-absorption by the seeds. When the seeds were placed in water at various temperatures, the initial rate of water intake was rapid, this being followed by a decrease, then by an increase and a later decrease. This double maximum in the rate of water-intake appeared in the result of each of sixteen tests. The purpose of this paper is to describe and discuss the experiments which led to these results.