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MOST poultrymen know that in mature Single Comb White Leghorn females the large comb lops over on one side of the head, frequently covering the eye. The question arises, hitherto unanswered, whether the combs lop to the right or left with equal frequency. Is the direction of the lop determined by heredity? Do some combs remain erect? Are hens with combs on the left side as desirable from the economic standpoint as those with combs lopped to the right, and are either superior to hens having upright combs? Although the answers to these questions have till now been unavailable, they might be considered so unimportant that a special experiment to obtain them would hardly be justified. However, merely by recording the direction of the comb lop for the breeding Leghorns and their progeny utilized in an extensive study of genetic resistance to disease, it has been a simple matter to . . .

IN PREVIOUS papers of this series it was shown that White Leghorns differ from heavy breeds in being much more resistant to extreme heat (Hutt, 1938) and to a deficiency of vitamin B1 (Lamoreux and Hutt, 1939). It has also been stated (Hutt, 1935Hutt, 1938Hutt, 1941) that White Leghorns are more resistant to pullorum disease than are heavy breeds. This fact is so well known to experienced poultrymen that it seemed almost unnecessary to substantiate it, but, because the statement, has occasionally been challenged, presentation of some of the evidence seems desirable. This is particularly so because, even in such extensive reviews as those of Reis and Nobrega (1936) and van Heelsbergen (1929) and in the monograph of Rettger and Plastridge (1932), there is no reference whatever to the fact that some breeds are more resistant to pullorum disease than others. Roberts and Card (1935) have already reported experiments indicating . . .

1. An investigation has been conducted to determine the mode of inheritance of frizzling in the domestic fowl and to substantiate or disprove the current theory that homozygosity for frizzling is lethal. 2. Two types of frizzling, ordinary and extreme, are differentiated. 3. Incubation records failed to show any evidence of a zygotic lethal factor being operative during embryonic development. It was found that no gametic lethal factors are involved. 4. Mating of ordinary Frizzles to normally feathered fowls produced the 1:1 ratio of parent phaenotypes expected in a back cross to a recessive. Offspring from matingsinter se of normally feathered fowls extracted from matings of Frizzle x Frizzle were all normal. 5. The progeny from matingsinter se of ordinary Frizzles gave a 3:1 ratio of Frizzles to Normals and in a random sample of this population the ratio of extreme to ordinary Frizzles was as 1:2. 6. Five extreme Frizzles were tested and proved to be homozygous for the character, producing, when mated with a normally feathered male, only chicks showing the ordinary type of frizzling. 7. Eighteen ordinary Frizzles were tested and found to be heterozygous. 8. Reciprocal crosses showed that the character is not sex-linked.

The data here presented definitely establish the fact that crest, dominant white and frizzling belong to the same linkage group. It is shown that these genes have the arrangement in the chromosome of Cr-I-F with approximately 12 per cent. crossing-over between Cr and I and 17 per cent. between I and F. Since the percentage of crossing-over between Cr and F is 29, the distance in the chromosome between Cr and F, as measured by the summation of the segments Cr to I and I to F, is practically identical with that secured by directly measuring the percentage of crossing-over between Cr and F. This indicates that little double crossing-over occurs in the approximate distance of 29 units on this chromosome. In segregation of these genes in birds heterozygous for all three, no double cross-overs were recorded in 284 gametes. Evidence is adduced to support the view that cerebral hernia is ordinarily the homozygous expression of crest, but a number of irregularities were found in the manifestation of cerebral herni...

THE incidence of malpositions found in chick embryos which had died after the eighteenth day of incubation has been reported as follows: From these data, and the similar reports of other workers based on smaller numbers or on “dead in shell,” it is obvious that malpositions are largely responsible for the peak of mortality occurring during the last three days of incubation. In the representative material reported by Hutt and Cavers (1931) based on the examination of all dead embryos from 24,660 fertile eggs incubated at two experiment stations in three years, malpositions in embryos of 18 days or older were apparently responsible for 24.4 percent of the total mortality. It is obvious that to reduce the present high embryonic mortality universally encountered in artificial incubation the origin of these malpositions must be discovered, as well as some means of eliminating them or of reducing their frequency. An investigation in . . .

DOUBLU-YOLKSD eggs are familiar objects, but, so far as the writer can determine, the voluminous literature on abnormal eggs contains only two records of specimens like the one illustrated in Plate 7 (upper figure). Description. The egg was left at this department without any record of its history, and by the time it was brought to the writer's attention, the donor could not be traced. The egg weighed 71.6 grams, which is almost 20 per cent less than the 86.26 grams given by Pearl (1910) as the average weight of 18 double-yolked eggs in his collection. It resembled other double-yolked eggs in shape, but differed in being apparently truncated at the large end and showing there a dark peduncle, not unlike the stem of a pear, which protruded through the shell membranes. The latter were covered with a thin encrustation of shell. There was no air cell and no shell at the larger end other than this slight deposit on the membranes. The latter were sunken so that, when the egg was held vertically with large end upward, the surface of the membranes was slightly concave. At first glance, it seemed as if the shell at the large end had been removed, leaving only the inner shell membrane, which would have formed the base of the air cell in any normal egg. Closer examination showed that it was more likely that the large end had never had any covering of shell other than the very thin layer over the membranes. This seemed probable because (1) the normal thick shell flared slightly outward where it terminated at the periphery of the membranous area, and (2) on dissection of that part, both inner and outer shell membranes were found. If the egg had ever been completely covered and some shell then removed from the large end, the outer shell membrane would have been lost with it. When a window was cut in the shell, the nature of the abnormality was evident. In addition to a normal yolk, the egg contained another that was still enclosed in its follicle (Plate 7). It was the twisted stalk of the latter that protruded through the membranes. The larger blood vessels in the follicle were quite distinct, as was the stigma, the crescentic area free of blood vessels which normally ruptures to release the ovum from the ovary. The abnormal follicle with stalk and contents weighed only 7.4 grams. It was spherical in shape, with diameters varying from 23 to 25 mm. These figures indicate that it was

GREAT differences in the response of individuals to different diets, or to certain deficiencies in the diet, are normally expected, and are commonly assumed to result, in part, from differences in genotype. Striking results of selection for resistance to a nutritional deficiency were obtained by Serfontein and Payne (1934) when, with only one generation of selection, they were able to segregate fowls 18.6 percent of whose chicks developed “slipped tendon” (perosis), as compared with 50 percent among chicks from parents which had been susceptible to the disorder. In view of a later study by Wilgus, Norris and Heuser (1937) we may assume that much of this difference was the result of differences in genetic resistance to a deficiency of manganese in the diet. A difference between breeds in their requirement for vitamin B1 (thiamine) was later demonstrated by Lamoreux and Hutt (1939). They found that White Leghorns consistently had a . . .

INTRODUCTION WHILE there is general agreement that some degree of heterosis is to be expected from crossing different breeds, and also from crossing inbred strains of one breed, there is still much to be discovered about (1) the ways in which that heterosis may be shown and (2) the amount of inbreeding of parent strains that is necessary to induce it. This report presents some evidence on both of these points. It comes from reciprocal crosses made in two successive years between two strains of White Leghorns which, although maintained for some years as distinctly separate strains, were only slightly inbred. STRAINS CROSSED The Leghorns crossed were of the C-Resistant and K-Resistant strains which, since 1935, have been bred by the authors for resistance to leucosis and, concurrently, for increased egg production, for eggs of about 58 to 60 grams, and for a body weight of about 2,000 grams. Details . . .

THE size of the comb in different breeds bears no direct relationship to the inherited ability to live and to lay. However, within any one breed the extent to which a rather large comb might interfere with feeding or be more prone to injury could indirectly affect a bird’s health or production. Dubbing to improve a cock’s chances in the fighting pit has been practised for a long time, and in colder climates males are often dubbed to eliminate the adverse effects of a frozen comb and wattles on vigor and fertility. It is surprising, therefore, that the dubbing of females has not received consideration until recent years. Perhaps the first attempt to evaluate the effects of dubbing females was that of an unknown poultryman who reported his findings in the Australian Poultry World. These were summarized subsequently by the Editor of the New Zealand Poultry World (Anonymous, 1942). In …

INTRODUCTION THE various breeds and varieties of domestic fowls, like most of those in other domestic animals, have been differentiated at the time of their establishment by characteristics of structure, size, and color rather than by variation in the physiological characters and functions by which their economic use is now measured. Association of some morphological character, or group of such characters, with a physiological one, without artificial selection for the latter. is comparatively rare in domestic animals although a number of such cases have been demonstrated in plants. The present paper reports an association between breed characteristics and an interesting psysiological character, the ability to withstand extreme heat. The unusual heat of July, 1936, in the United States caused abnormally high mortality in the human race, with deaths, for the week ending July 18, 64 percent higher than in 1935 for 86 cities with population of 37 millions 1 . Corresponding figures for . . .

DIFFERENCES between breeds in nutritional requirements were first reported by Payne et al. (1932), who observed that their Rhode Island Reds were much more susceptible to perosis than were their White Leghorns. Since then considerable evidence of genetic variation in nutritional requirements has accumulated and this has been reviewed elsewhere (Hutt, 1949). With respect to thiamine, the tests of Nichita and Iftimesco (1934) with adult White Leghorns, and those of Nichita et al. (1934) with Rhode Island Reds, indicated that the latter breed is more susceptible than the former to a deficiency of vitamin B1. This was confirmed by Lamoreux and Hutt (1939), who eliminated any possible influence of the breed difference in size by testing chicks of the two breeds instead of adults. Subsequently Scrimshaw et al. (1945) found that White Leghorns put more thiamine in their eggs than hens of the heavier breeds when both kinds are maintained …

OVULATION and the subsequent laying of a normal egg, usually within 26 hours, are preceded and accompanied by certain changes in the body of the hen. The external characters that are associated with an active state of egg production are well known and are used as the basis for the periodic culling of commercial laying flocks. By the absence of external changes considered indicative of egg production, one is able to identify non-layers and to remove them from the flock, if so desired. It is customary to consider as layers those birds which show the external characteristics associated with egg production. We have learned, however, that some birds behave as though they were laying, and show appropriate changes in body condition, without actually producing an egg. This paper presents the pertinent findings when groups of such birds were subjected to study. SOURCES OF DATA Among large populations of pedigreed White …

INTRODUCTION FOR the past ten years the junior author has been breeding fowls resistant to disease, particularly to lymphomatosis. During the course of the work it became evident that limiting factors of great importance were (1) the relatively small numbers of breeding birds that could be tested in any year, (2) the difficulty of selecting unproven cockerels that would transmit viability, and hence (3) the very small number of good, proven sires available for use in a second year or longer. When the standards set up require that the sire’s progeny must excel the flock average, not merely in viability but also in egg production, and at the same time be satisfactory in egg size, in body size and in hatchability of eggs, it is unusual to find even a quarter of the cockerels tested in one year eligible for re-use in the next. Furthermore, when the flocks under test . . .

OTHER things being equal, the amount of heat lost by a warm-blooded animal is directly proportional to the surface area of that animal. The surface area, however, is not directly proportional to the weight, but varies approximately as does weight213. This means that the surface area per unit of weight is much greater in the small animal than in the large one, and ipso facto, that in homoiothermic animals the problem of maintaining body temperature above that of the environment is more difficult for small individuals than for large ones. Kleiber (1932) calculated that if a mouse. and a steer had the same heat production per gram of body weight, and if both were required to maintain the same temperature, the mouse would need a specific insulation twenty times that of the steer. The extensive data of Wetmore (1921), including 1,558 records of body temperature for 327 species of birds, indicate that small birds maintain temperatures just as high as those of larger species. For example, the mean temperature in ten species of Paridae (tits and chickadees) was 107.90 F., exactly the same as for fourteen species of Corvidae (jays, magpies and crows). Determinations of the metabolic rates of forty-five birds representing thirty-two different species ranging in size from 0.02 to 17.6 kilograms, made by Benedict, Giaja, Terroine and others, as summarized by Brody (1932, pp. 89-97), show that in birds, as in mammals, the metabolism per unit of body weight is highest in the smallest species and decreases with increasing body size. This indicates that maintenance of high temperatures by small birds is accomplished in part by an increase in the metabolic rate. However, the amount of insulation may also be an important factor. If this be so, the greater insulation needed by the smaller birds to maintain temperatures the same as those of large ones, which are from 30 to 120 F. higher than those of mammals, might be obtained by increased length of the feathers, but the resultant disproportion between size of body and length of feathers would probably interfere with flight and hence have little 'survival value.' Since the type of feather changes little within any one order, or group of birds, it is probable that any additional insulation needed by small birds is provided by an increase in the number of feathers per unit of body surface. On theoretical grounds, therefore, there should be many more feathers per unit of area in the Chickadee weighing eight to ten grams than in the Blue Jay of about ten times the latter weight. It follows that, since the surface area per unit of weight increases with diminishing body

DURING the first 8 years of selection at this laboratory for genetic resistance to leucosis combined with other traits of economic value, it was our practice to leave each male in his breeding pen throughout the entire hatching season of 8 to 10 weeks. By 1942 it was evident that, while marked improvement had been made in the first three years, progress thereafter had been almost nil. It was equally clear why improvement had stopped. We had tried each year to find enough good proven sires to head at least 25 percent of the breeding pens. During the first 5 years, the average number of pens used for the two resistant lines together was only 13.2, but, among the 10 cockerels or so tested annually, it was seldom possible to find 3 or 4 proven sires that could be used again without considerable misgivings. In 1940 to 1942, the average …

INTRODUCTION FOUR years ago, Hutt et al. (1941) reported results for the first four generations of White Leghorns bred for resistance to disease, particularly to lymphomatosis. These showed that, whereas deaths from neoplasms during the test period were 16 percent in the unselected population with which the experiment started, in the fourth generation such deaths had been reduced to 12 percent. This decrease, really by a quarter of the original proportion, seemed significant, not merely because it was based on 785 birds, but because, at the same time, deaths from neoplasms were more than twice as frequent (26 percent) in the stock bred for susceptibility. Moreover, the decline of total mortality from 64 percent in the unselected population to 38 percent in the fourth generation permitted a higher proportion of the latter to develop neoplasms had they been genetically susceptible. The fact that only 12 percent did so is more . . .

Various studies upon the development of eggs of fowls and of pigeons have shown that the processes of formation of the egg and of development of the embryo during the passage of the egg down the oviduct are continuous throughout the twenty-four hours of the day. They are involuntary reactions. On the other hand the actual laying of the egg is a reflex for which the necessary sensory stimulus usually does not occur while the hen is on the roost at night. This means that if an egg be fully formed and ready to lay at 2 a. m ., it is retained in the uterus till the following morning. The embryo of such an egg (when fertile) would presumably have undergone some six hours further development than if the egg had been fully formed at 2 p. m . and had been laid at 2:30 p. m . Such a view is . . .

IN A PREVIOUS communication by one of us (F. B. H., 1938), it was pointed out that neoplasms caused over 38 percent of all deaths among 1,922 fowls dying during the six-year period, 1931–37, at two laying tests in New York. It was also shown that in this same population 87 percent of all deaths were caused by diseases thus far not amenable to control by sanitation, immunization, elimination of carriers, and other orthodox procedures currently recommended for the control of poultry diseases. Because of this situation, an experiment was begun in the spring of 1935 to test the feasibility of breeding strains of White Leghorns resistant to some of these diseases. A brief report of the first three years of this work was given earlier by Hutt, Bruckner, and Cole (1939). In the present paper, we present results of the first five years’ work. These include the unselected . . .

MALPOSITION III (head under left wing) is probably the most important malposition because of its frequency, which may range up to 5 percent of the embryos still alive after 18 days of incubation, and the fact that it is almost always lethal. Its cause is quite unknown, except that it is more frequent in eggs incubated with the large end up than in those incubated horizontally (Byerly and Olsen, 1936). During examination of some 40,000 unhatched eggs it appeared to the writer that malposition III was more frequent in the larger eggs, and, since definite information on this point was lacking, an investigation was undertaken to determine the relationships, if any, between the frequencies of various malpositions of the embryo and the size and shape of eggs. MATERIAL AND METHODS During 1933 and 1934 all eggs incubated in the regular hatches at the Minnesota Agricultural Experiment Station were utilized. The . . .

Daily doses of 4 mg. thyroid iodine per 1000 and 2000 gm. of body weight proved lethal to male and female fowls. Daily doses of 4 mg. thyroid iodine per 3000 to 5000 gm. body weight caused loss in weight in males and females. The same amount of thyroid iodine to 7000 gm. of body weight caused loss of weight in a cockerel but not in a hen. Smaller doses had no effect on the weight in either sex. All doses, even 4 mg. thyroid iodine to 10,000 gm. body weight, caused hen feathering in the males. Depigmentation was quite marked in the case of the heavier doses, but less evident in that of the smaller. In general, depigmentation was most evident in the birds which declined in weight. The minimum daily dose necessary to produce marked depigmentation was 4 mg. thyroid iodine to 5000 gm. of body weight. This explains why several investigators have not obtained the depigmentation described by Giacomini and Zavadovsky. On doses of 0.8 mg. thyroid iodine per bird or less, Cole and Reid, and Crew observed production of darker feathers. On much larger doses Giacomini, Zavadovsky and the writer observed depigmentation. It would seem that the smaller doses of thyroid cause increased production of melanin, presumably by the general increase in metabolic processes, but that at a certain stage (which this experiment indicates to be around 4. mg. thyroid iodine per 5000 gm. of body weight) the production of pigment is arrested. The use of a definite dosage of thyroid iodine based on body weight has led to consistent results and to an explanation of some of the discrepancies which have previously appeared in the literature.

THE persistent claim by Waters (Waters and Prickett, 1944; Waters, 1945; 1947) that avian leucosis is spread by transmission through the egg to the chick has now been extended to include a theory that chicks are infected in the incubator by dissemination there of the causative virus (Waters and Bywaters, 1949). These themes have received so much attention by the world’s poultry press that many poultrymen are now hoping to be able eventually to control the disease by the detection and elimination of hens carrying the virus or by disinfection of the incubator. In our opinion, the data presented hereunder show (1) that it is very unlikely that the disease is transmitted through the egg, (2) that any such transmission that may occur is of no significance whatever in the practical control of leucosis, and (3) that the all-important factors in determining the severity of this disease in a flock . . .

IT IS fitting that we members of the Poultry Science Association assembled here for the thirty-second annual meeting of our society should devote a little time to the consideration of the next generation. It is probable that 20 years from now more than half our membership will be made up by persons who are now in high schools or at still earlier stages in the long process of learning. In the next few years these boys will be entrusting to us their college education. What kind of training shall we recommend to them? Let us hope that we may profit by the mistakes of the past, that we may see ahead only a little way in the future, and that we may be able to turn out men who will be a credit to themselves, to their institutions, and to our profession. I have been asked to discuss the requirements . . .

By breeding tests of albinotic fowls found in New York State, in Massachusetts, and in Indiana, it was shown that all three were genetically identical, and were caused by a mutation in the sex chromosome. In one case, the mutation occurred in White Leghorns; the others were in Barred Plymouth Rocks. Reasons are given for assuming that the three mutations, though genetically identical, arose quite independently.

IN CONNECTION with other studies involving variations in the temperatures of chicks during the first two weeks of life, it was necessary to determine first the normal variations and environmental conditions affecting them during that period. So far as could be ascertained the only data on this subject obtained with adequate numbers of chicks under normal conditions of brooding and diet are the unpublished figures of Fronda (1922) which indicate that at one and two weeks of age the temperature is about 3°F. higher than at hatching. Card’s (1921) unwatered chicks, kept to five days, showed considerable diurnal variation in temperature. The present writers sought to find (1) possible sources of error in determination of temperature, (2) an adequate technic for temperature determination in baby chicks, (3) normal temperature variations in relation to age, weight, sex, and breed of the chick from hatching until it approaches the normal temperature of . . .

THE use of multiple shifts for testing large numbers of cockerels has proven of value as a method for recognizing superior sires (Hutt and Cole, 1955). Males proven to be superior by performance of approximately 50 daughters are then used in subsequent years throughout an entire breeding season of 8 to 9 weeks and produce families two to four times as large. The chief objection to the shifting or replacing of males in the breeding pens is that for a period of time the paternity of the chicks hatched may be in doubt. In practice, this uncertainty need not be a deterrent to the use of multiple shifts. The actual error in assignment of paternity is so low that it would not influence the evaluation of either parent. PREVIOUS REPORTS Crew (1926) exchanged males in two breeding pens and measured the speed with which the semen of the replacing male …

VARIATIONS in the level of ascorbic acid in the blood of hens should be of considerable interest because of their possible relationship to genetic differences in the metabolism of that vitamin. Plimmer and Rosedale (1923), Emmett and Peacock (1923), and Hart et al. (1925) early demonstrated that ascorbic acid is not necessary for the growth of chickens. Holmes et al. (1939, 1940) and Ludwig (1940) have shown that it is not necessary for normal laying. Satterfield et al. (1940) found no relationship of the ascorbic-acid content of chicken blood to 14 different pathological conditions. In most of these studies a single breed was used. Apparently no one has investigated the possibility that breeds might differ in metabolism of ascorbic acid. In the fowl such differences might exist quite independently of dietary factors. Nichita and Iftimescu (1934), Nichita et al. (1934), and Lamoreux and Hutt (1939) showed that breed differences do . . .

Analyses of records of official pedigree breeding stations in Lancashire and in Northern Ireland show that the ability of White Wyandottes to reproduce is subnormal in comparison with White Leghorns and Rhode Island Reds. A total of about 15,000 eggs for each breed is involved, and the samples came from many different farms. The numbers of chicks hatched per 100 White Wyandotte eggs incubated were 12.5 and 11.8 less than for White Leghorns and Rhode Island Reds, respectively, at one station and 4.0 and 8.2 less at the other. These differences apparently resulted chiefly from infertility, though early embryonic mortality may also have been a factor. The subnormal reproduction is attributed to the pleiotropic action of some gene, or genes, determining the characteristics of White Wyandottes, or to linkage of deleterious genes with those making the breed.

HISTORY OF THE EXPERIMENT IT WAS apparently recognized by Woods (1908), director of the Maine Agricultural Experiment Station, as long ago as 1898 that an increase in annual egg production is not convincing evidence that genetic selection for high fecundity is effective, unless selection for low production is practiced concurrently so that the effects of changes in housing, feeding, and other details of management can be evaluated. Two experiments were therefore planned in which the effectiveness of selection for either high or low egg production could be studied at the Maine station. The first was designed to improve egg production by selecting as breeders females which laid 150 eggs or more, and males whose dams laid more than 200 eggs during their first year of production. This experiment was conducted by Professor Gowell during the nine years beginning in 1898. The results were disappointing; the general level of egg production . . .

Polydactyly was found to be linked with multiple spurs and with duplex comb. The arrangement of these genes and the approximate crossover distances separating them are: D 28 M 33 Po. The amount of crossing over measured between D and Po was 42 per cent. and there were 9.3 per cent. double cross overs. These determinations were made in backcross populations showing a normal 1 : 1 ratio of polydactylous to four-toed birds. It is shown that interpretation of linkage tests with Po is difficult when, as frequently happens, inhibiting genes prevent the manifestation of polydactyly in heterozygotes. Genes suppressing this mutation seem also to suppress multiple spurs. A summary is given of published evidence and new data showing that D and Po, at opposite extremes of this linkage group, are apparently independent of four other autosomal linkage groups and of seven other genes with which both have been tested.

IT IS now generally recognized that there are two distinctly different means of reducing mortality in fowls from lymphomatosis and related diseases. One of these is to breed strains that are comparatively resistant. The feasibility of doing so has been demonstrated by Hutt et al. (1941) and by Taylor et al. (1943), but the utilization of this method is limited by the fact that few poultrymen are in a position to maintain the necessary exposure to the disease and to carry out over a period of years the progeny testing, with its inevitable record keeping, that is required in breeding of this kind. The other method is to rear the chicks in complete isolation from adult fowls during the growing period. The efficacy of this procedure was demonstrated experimentally by Kennard and Chamberlin (1936) and by Johnston and Wilson (1937). It has been confirmed in practice by many poultrymen. Disadvantages . . .

Partial suppression of the frizzled plumage of heterozygous Frizzles is induced by a recessive autosomal gene, mf, which is independent of the gene for frizzling.

DURING four crossings of the North Atlantic Ocean made in the past four years, the writer has made many notes upon the birds which could be seen from the ship. A few of these are familiar to most Canadian and American ornithologists but most of them are seldom seen except by dwellers along the rocky coast of the continent and still others are found only in European waters. It is hoped that the notes below will give the intending ocean traveller some idea of what species are likely to be seen by careful observation from the deck, and of the regions in which each should be sought. The sailing dates were as follows

In an attempt to learn more of the properties and functions of the thyroid gland, several investigators have tried feeding fresh or desiccated thyroids to fowls. During 1924 and 1925 experiments of this nature were made by the writers. In view of the varying reports of other investigators, our results are considered of sufficient interest to warrant their presentation. They include effects of thyroid feeding on moulting, egg production, weight, plumage color and plumage structure. MOULTING Forty White Leghorn hens were divided into two equal lots and fed identical rations. To make the environment natural and equal for both lots, ten birds to receive thyroid and ten controls were put in each of two identical colony houses, both of which had out-door yards. For a period of six weeks, beginning November 1st, the twenty thyroid-fed hens were given desiccated thyroid (Armour and Co., 0.2% iodine) at the rate of 196 . . .

During the past five years there has been sent to this department a number of male fowls suspected by their owners of having been originally females and of having turned into functional males in a manner similar to that of the cases described in the fowl by Crew5 and in the pigeon by Riddle.17 In nearly every instance it has been impossible to verify the accuracy of the case history by breeding tests or by post mortem examination. Sex dimorphism, in size as well as in plumage and colour, is more conspicuous in the Gallinae than in the majority of other birds. It seemed possible that this dimorphism might be so great that skeletal measurements would give a clue to the original sex of such individuals as those mentioned above. It was recognized that the range in length of any single bone in one sex would probably overlap the range . . .

THREE recent papers in this journal by Turner et al. (1945, 1945a. 1946) and a review by Reineke (1946) report experiments which led these writers to conclude that iodinated casein, a substance having the properties of thyroxine, has a marked stimulatory effect upon the production of eggs by domestic fowls. In most of the experiments this effect was believed to be exerted chiefly during the months of late spring and early summer, when production normally declines, but in one test (Turner et al., 1946, Lot IV) the treated birds laid better throughout the year. Since any such effect would have considerable economic value, it seemed desirable to repeat the experiments. THE EXPERIMENT Birds.—Single Comb White Leghorn pullets of the C and K strains resistant to lymphomatosis (Hutt and Cole, 1947) were utilized. The total number enrolled at the start of these trials was 401, these being divided in four . . .

RAYMOND PEARL died on November 17, 1940, at the age of 61 years. During a decade in charge of poultry investigations at the Maine Experiment Station he made more contributions to poultry science than most people are likely to make in a lifetime. It seems desirable, therefore, to have some record of his achievements in that period and to bring together in one place a list of his publications concerning poultry, which were published in many different journals. BIOGRAPHICAL NOTES Raymond Pearl was born at Farmington, New Hampshire, on June 3, 1879. He graduated from Dartmouth with the degree A.B. in 1899 and from Michigan with the Ph.D. in 1902. For four years thereafter he was on the staff at the University of Michigan as instructor in zoology, but during the last of those four years he visited laboratories in Europe. At University College, London, his natural interest in variation . . .

Coles (1955) stated that “birds in their hen year failed to transmit resistance (to leucosis) because of incomplete ability to do so with increasing age” and that “a parent bird may increasingly fail with age to transmit genetic resistance to its offspring.” Age has no influence upon the genotype of an individual bird nor does it determine which genes are distributed to the functional gametes. Coles did not specify any mechanism by which age of the dam might influence resistance of her progeny, and the data given in support of his theory were scarcely conclusive. However, since in mice a non-chromosomal influence of age of dam on the incidence of spontaneous leukemia in her progeny is known (MacDowell, Potter and Taylor, 1945), it seemed desirable to examined our records for any evidence that might support Coles’s theory. From the records of our White Leghorns for the six years, 1949 to …

ABNORMAL eggs of various kinds have interested biologists for centuries. The literature in that field is now so voluminous that it might be expected to contain descriptions of all kinds of abnormal eggs that are likely to occur. However, so far as the writer has been able to determine, the abnormality described below has not previously been reported. The egg shown in Figure 1 was found on April 22, 1937 in a trapnest at this laboratory. It had evidently just been laid by the White Leghorn pullet, C-511, found standing over it in the nest. It consisted of an apparently fully developed ovum completely enclosed in an unruptured ovarian follicle. The latter seemed normal in every respect and was covered with the usual extensive network of blood vessels. The stalk of the follicle was 27 mm. long and it tapered down almost to a thread at the end where it . . .

THE extent to which strains of fowls bred for genetic resistance to disease can be generally utilized depends in part on the answer to an important question. Are such resistant stocks equally or similarly resistant when transferred to areas other than that in which they were developed? With respect to unselected stock, there is ample evidence that strains which are satisfactory when lightly exposed in one environment can experience high mortality when severely exposed elsewhere. There is little evidence, however, on the degree to which strains bred for resistance to disease maintain that resistance when transferred to some other region. This question is particularly important with respect to leucosis, because genetic resistance and rearing in isolation are the only means known for controlling that disease. To answer it, in part at least, an exchange of stock was arranged between the Alabama and New York (Cornell) Experiment Stations, at both of . . .

THE sex-linked alleles, K and k, induce remarkably different rates of feathering which are most evident in young chicks. The effects of these genes and their economic importance have been discussed elsewhere (Hutt, 1949). It would not be surprising if the influence of K and k on the growth of cells in the feather follicles were merely the outwardly visible manifestations of more general influences affecting the bird’s physiology, but no such effects have yet been conclusively demonstrated. Contrary to an earlier suggestion, it has been shown by Hays (1951), Hale (1952) and Godfrey and Farnsworth (1952) that slowly feathering chicks do not differ in rate of body growth from those that feather rapidly. Since pullets of these two types do not differ in age at first egg (Hays and Spear, 1951), it seems probable that K and k do not influence the physiology of the endocrine glands. An indication …