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THE monosaccharide composition of isolated cell walls of strain 7–11–05 of Chlorella pyrenoidosa Chick, an organism proposed for life-support systems in space travel, was examined. The two principal methods used were thin-layer chromatography and paper chromatography, accompanied by appropriate staining.

THE task of testing and localizing enzymes in a protein mixture subjected to paper electrophoresis is a tedious one. This is particularly true in a fractionation study where the number of tests may be numerous. During the course of such an investigation of the various carbohydrases in an Aspergillus niger fermentation, it became necessary to employ a rapid qualitative test for the detection of these enzymes. Keilin and Hartree1 have reported that glucose oxidase (notatin) can be successfully used for the quantitative assay of various carbohydrases. Monod and Torriani2 employed notatin to determine glucose in their studies of amylomaltase. Recently, Whistler et al. 3 showed that D-glucose in corn syrups can also be quantitatively estimated by using notatin. The latter enzyme oxidizes glucose to yield two products—gluconic acid and hydrogen peroxide.

THE study of animal haemoglobin types is developing rapidly and the results obtained in various species have recently been summarized by Huisman, van der Helm, Visser and van Vliet1. However, the electrophoretic mobility of hippopotamus haemoglobin does not seem to have been studied before, possibly because of scarcity of materials. We have had the opportunity to examine haemoglobin samples from the East African hippopotamus, Hippopotamus amphibius L.2, obtained during a controlled reduction in a hippopotamus population.

PAPER-PARTITION chromatography of tissues of genetically known strains of Drosophila melanogaster as well as those of certain plants has shown that each strain gives a constant and distinctive pattern. The chromatographic patterns of heterozygotes carrying recessive genes can be easily distinguished from those of either parental homozygous strain, even though the phenotype of the heterozygote is indistinguishable from that of the homozygous dominant. This is the case for: (a) the fluorescent patterns observed under ultra-violet light in the chromatograms of adult Drosophila melanogaster heterozygous for the following mutants: bent, eyeless2, short-vein, spineless-aristapedia, vestigial; (b) the ultra-violet-fluorescent and the ninhydrin-positive patterns of root-tip smears of heterozygotes for the mutant male-sterile2 in tomato1; (c) the ultra-violet-fluorescent and the ninhydrin-positive patterns of root-tip smears and leaf extracts of heterozygotes for the yellow-green mutant of musk melon2 (see also chromatogram).

XANTHINE dehydrogenase from Drosophila melanogaster is of particular interest since mutants at two separate loci lack this enzyme1 while a mutant at a third locus produces about 25 per cent of normal activity2. In an effort to detect strains of flies with genetically altered forms of xanthine dehydrogenase we devised a technique involving paper-strip electrophoresis in which this enzyme is located after electrophoresis by spraying the strip with the enzyme's substrates, incubating it at 25° C, and then using paper chromatography to separate the fluorescent product from the substrate which also fluoresces. This technique is very simple, and has potential application to other enzymes. Paper electrophoresis of xanthine dehydrogenase in rat serum has previously been reported using the technique of elution and direct assay3,4.

WE have already described a fortuitous combination of events which led to the discovery that American newspapers and other paper products contain a potent analogue of the juvenile hormone of the European bug, Pyrrhocoris apterus L. (Heteroptera ; Pyrrhocoridae)1. When reared in contact with ‘active paper’ or when exposed to surfaces impregnated with extracts of the ‘paper factor’ (PF), fifth-stage Pyrrhocoris larvae undergo one or more supernumerary larval moults and finally die without completing metamorphosis or attaining sexual maturity. This same result is observed when 1 µg of partially purified PF is topically applied to young fifth instar larvae1,2.

IN several recent publications, separation of the alkaloids of the South American Strychnos into a great number of constituents by paper chromatography has been recorded1,2. The most successful solvents for two-dimensional analysis yield, however, almost the same sequence of spots. Thus it was considered desirable to find methods of separation which gave sequences different from those obtained by partition chromatography.

IN connexion with the chromatographic separation of alkaloids of Chelidonium maius L.1, I found alkaloids giving rather big spots with a tendency to form tails. This is connected, among other things, with the dissociation constant (K B), the value of which influences the course of the chromatographic process, organic electrolytes having different values of K B in the water phase and the organic phase of dissociation.

IN the course of studies on the aromatic constituents of Theobroma cacao L., a method has been developed for the separation by one- and two-dimensional paper chromatography of the naturally occurring substituted cinnamic acids, which is also applicable to many other aromatic acids of plant tissue.

EVIDENCE for the presence of growth substances in the root extract of water hyacinth (Eichhornia speciosa Kunth), presumably related to the rapid multiplication of the weed, has been reported previously from this laboratory1. A comparison of the effects of the extract with those of indole acetic acid or gibberellic acid indicated a different substance or substances present in the extract.

MOST methods used for the estimation of strychnine in nux vomica lead to gross inaccuracies due to brucine interference. Even oxidation of brucine with nitric acid under optimal condition (5 min. at 60° C.) leads to errors due to partial destruction of strychnine1. Gravimetric estimations also require amounts greater than 0.1 gm. in the sample1.

MATERIALS composed of American paper-pulp have been shown to contain an extractable, heat-stable lipid which exhibits high juvenile hormone activity when topically applied or otherwise brought into contact with the European bug, Pyrrhocoris apterus L. (Heteroptera; Pyrrhocoridae1,2). The active principle is synthesized by certain species of pulp trees—more particularly, the American balsam fir (Abies balsamea). The ‘paper factor’ (PF) proves to be an extremely potent analogue of the juvenile hormone of Pyrrhocoris apterus3. Yet, so far, it has proved completely inactive when tested on other laboratory insects including two other species of Heteroptera—Oncopeltus fasciatus (Lygaeidae) and Rhodnius prolixus (Reduviidae)1,2.

SEVERAL years ago, Gibbs,1 summarizing contributions of biochemistry to plant taxonomy, recognized the importance of the then relatively new techniques of paper chromatography and forecast their wide application, to systematics. Although a number of workers have applied chromatographic techniques to taxonomic problems in both botany and zoology2, the use of these techniques is not nearly commensurate with their potential value, perhaps because the cooperation of taxonomists and persons trained in biochemical analysis has been slow to develop. The present communication constitutes a brief description of work currently under way which is to be reported in greater detail elsewhere;3 the chomatographic analysis of individuals from a natural hybrid swarm of Baptisia laevicaulis × B. viridis (family Leguminosae), and correlation of these data with a similar analysis of the parental species collected in pure populations. Three other species of Baptisia were also examined chromatographically. Since this genus contains about 30 species of wide occurrence in the eastern United States, and hybridization among these species is common, it is highly probable that the scope of the present investigation will be extended. In this study we were particularly concerned with the recombination of biochemical components peculiar to each parental species among the hybrid and back-crossed individuals.

THE early stages in the life-history of recent crinoids have always been regarded with interest, because it was hoped that they would throw light on the evolution of this class, so rich and various in ancient seas, and on its relation to the other very differently fashioned classes of Echinoderma. Unfortunately, the only forms that have up till now furnished material for the em-bryologist are the unstalked comatulids, or feather-stars, and in the past such material has come from but a single genus, and from only three closely allied species of it—Antedon bifida of our own coasts, A. mediterranea, and A. adriatica. The accounts of their development by W. B. Carpenter, Bury, Seeliger, and others have shown slight differences, due, in part, probably to specific distinctness of the material. Even if it were not feasible to obtain the early stages of any stalked crinoid, still a study of other species, representing other genera of comatulids, was much to be desired, since it might then be possible to infer which features were peculiar to Antedon and which were common to comatulids generally, if not to the whole class Crinoidea. Such a study has now been made by Dr. Morten-sen, who has obtained a fairly complete series in four genera, and the pentacrinoid larvae of two others. His results are set forth in clear English with his usual care, and the memoir is illustrated by admirable drawings from his own pencil. His many interesting results are discussed in a “General Part” which demands the attention of professed morphologists. Here we shall select for comment a few observations that bear on the past history of the class. Papers from the Department of Marine Biology of the Carnegie Institution of Washington. Vol. xvi. Studies in the Development of Crinoids. By Th. Mortensen. (Publication No. 294.) Pp. v + 94+xxviii plates. (Washington: The Carnegie Institution of Washington, 1920.) 6 dollars, post free.

IN the course of our investigations of Echinocystis lobata seeds, it became desirable to locate triterpenoid glycosides on paper chromatograms by means of a colour reaction. A modification of the Liebermann–Burchard test described by Neher and Wettstein1 was unsatisfactory for this purpose. We found that the original Liebermann–Burchard reaction applied to paper chromatograms with comparatively little alterations gave more satisfactory results, permitting a reliable detection of the spots.

Biochemical Differences between Inbred and Outbred lines of Drosophila melanogaster studied by Paper Partition Chromatography

ON reading the article entitled “Juvenile Hormone Activity for the Bug, Pyrrhocoris apterus”, by Slama and Williams1, I was struck by a likely correlation.

DURING the course of an investigation into the chemistry of the cell wall of Penicillium notatum an unusual amino sugar was detected in acid hydrolysates of the walls. It was present in only small amounts, but was easily visible by paper chromatography. The material was isolated from a 4 normal hydrochloric acid hydrolysate (carried out at 100° C for 24 h) and was purified by elution from Whatman 3 MM paper using solvent system B. It gave a positive reaction with the silver nitrate1, aniline phosphate2, ninhydrin and Elson–Morgan3 sprays, suggesting that the compound is probably a 2-deoxy, 2-amino sugar.

RECENTLY, several articles have been published on the multiplicity of cellulase. Using paper chromatography Jermyn1 found eight components in cellulase from Aspergillus oryzae, each with cellulolytic activity. Reese and Gilligan2 found, also with chromatographic techniques, three components in Myrothecium cellulase, whereas Miller and Blum3, using starch electrophoresis, found at least eight components in this product. Grimes4 isolated from Myrothecium cellulase six components, of which possibly three had cellulolytic activity, and Thomas5 found seven protein fractions by paper electrophoresis. These facts are puzzling. Whitaker6 succeeded in isolating a homogeneous protein from crude Myrothecium cellulase which exhibited all the activities of the crude product, so there is a possibility that cellulase is a single enzyme. However, this has never been confirmed.

IT has been reported previously1 that the short-day plant, Maryland Mammoth tobacco, will flower under long day-lengths (14½–15½ hr.) if exposed to varying dosages of γ-rays. Recently, we have been investigating the effect of γ-radiation on the endogenous level of the indole compounds occurring naturally in leaf, stem, root and apical tissues of γ-irradiated and normal Maryland Mammoth tobacco. Large quantities of these tissues (300–1,000 gm.) have been extracted with absolute ethanol, employing a technique for extraction and paper chromatography as described previously2. Microlitre quantities of the extracts, after acidification and extraction with ethyl ether, were spotted on Whatman No. 1 filter paper and chromatographed in seventeen different solvents. Colours were developed with p-dimethylaminobenzaldehyde. 3-Indoleacetic acid was not detected in any of more than thirty-five individual extractions of leaf, stem, root or apical tissues of normal or γ-irradiated Maryland Mammoth tobacco. However, an unidentified indole compound was found in the leaf and apical extracts with R F values as shown in Table 1.

ISOLATED chloroplast preparations offer great advantages in the analysis of carbon pathways of photosynthesis because the system is not complicated by non-chloroplast metabolism, and kinetic analyses1 can be made which are difficult with whole leaves2. Unfortunately the slow diffusion and equilibration of CO2, HCO−3 and CO2−3 in the suspension medium is a serious disadvantage in gas exchange or 14CO2-12CO2 pulse-chase experiments3, but this difficulty can be overcome by using a thin film of concentrated chloroplast suspension spread on a non-absorbent support in the form of an “artificial leaf”. Recent experiments by Coombs and Baldry have shown that pea and spinach chloroplast preparations supported on filter paper were stable only for periods of up to 10 min4. We have used Acetabularia mediterranea Chloroplasts on filter paper to analyse the products of short term (1 s to 5 min) 14CO2 fixation, but we found them insufficiently stable for longer experiments or gas exchange measurements. We have overcome this difficulty, however, by supporting Chloroplasts on a non-absorbent grid instead of filter paper.

ANTIMONY pentachloride has been used as an agent for the detection of steroids in paper chromatography by a number of investigators1–4. It has been found that antimony pentachloride is a useful agent for detecting certain digitalis compounds (digoxin, digitoxin and digitoxigenin) on paper chromatograms.

USING paper chromatographic methods it has been shown that, following digitoxin administration to rats, the urine contains small amounts of unchanged digitoxin together with larger quantities of two cardioactive metabolites previously designated metabolites C and G 1,2. Human urine collected for 12 hr. from normal adults after an oral dose of 1 mgm. of digitoxin has now been found to contain some unchanged digitoxin as well as apparently larger quantities of two metabolites. The two metabolites when eluted from paper and rechromatographed using two systems of paper chromatography could not be separated from metabolites C and G.

VARIOUS β-globulin types have been demonstrated, using starch-gel electrophoresis, in several species of mammals, namely, man1, cattle2, sheep3, goat4 and horse5. The present communication reports the discovery of similar variations in two species of monkey, Macaca mulatta and M. irus. Variations in the monkey β-globulins were initially detected by paper electrophoresis using barbital buffer at pH 8.6. However, the β-globulins were much better resolved when starch-gel was used instead of paper.

IT has been shown by paper electrophoresis that genetically different types of β-lactoglobulin1,2 and α-lactalbumin3,4 occur in cow's milk. While genetic polymorphism of β-lactoglobulin is general among the cattle of different countries, that of α-lactalbumin has only been observed in two breeds of African zebus, the Nigerian White Fulani3 and the boran4 cattle of Kenya, but not in Icelandic, British3, Danish5 and North American6 (Holstein) cattle. Blumberg and Tombs noted the Nigerian White Fulani cattle to be similar in appearance to the ‘Brahmin’ cattle of the East, which were probably brought into Africa by the nomadic Fulani people, and suggested that α-lactalbumin-A might serve as a marker by which the affinities of the zebu cattle, and indirectly of the Fulani people associated with them, could be traced. We have now examined the α-lactalbumin and β-lactoglobulin polymorphism in Indian zebu cattle with the view of getting further information on this aspect. Moreover, from a comparison of electrophoretic patterns of non-casein proteins of African zebu3 and Indian buffalo milk7, the mobilities of zebu α-lactalbumin-A and of the single buffalo α-lactalbumin appeared to be approximately the same. This indicated that these two proteins might have closely similar physico-chemical properties as has been observed7–9 in the case of cow β-lactoglobulin-B and the single buffalo β-lactoglobulin.

THE replication of the RNA-containing bacteriophages has been found to involve specific replicases, partly coded by the phage genome (reviewed in refs 1 and 2). The replication proceeds by way of a partially double-stranded intermediate form, and the replicases must presumably recognise the 3′-terminal regions of the RNA (+) and (−) strands as start points for copying1,2. There is also evidence that the Qβ replicase recognises a specific internal region of the Qβ RNA molecule, which is involved in forming a replicative complex3. Replication of the smallest animal RNA viruses, the picornaviruses, also requires specific replicases, and has a mechanism4–7 which is not dissimilar to that of the RNA phages, as far as it has been elucidated. We have been studying nucleotide sequences of regions of a picornavirus RNA which might be specifically recognised by its replicase, or have specific roles in the replicative process, in the same way that such sequences have been characterised in the RNA phages1–3.

IN recent years, several workers have paid a great deal of attention to the purification and the cellulolytic activity of aerobic cellulose-decomposing bacteria, especially Cytophaga and Cellvibrio. Isolations have generally been carried out by direct plating of soil suspensions on precipitated cellulose agar, and by enrichment cultures on silica-gel filter paper or on filter paper partly immersed in a liquid mineral medium. With the former method, most of the dishes are invaded by moulds and generally the formation of lytic zones is not very obvious.

SAP from the sieve-tubes of the willow Salix viminalis was obtained using the mouthparts of the willow aphid as described by Kennedy and Mittler1 and us2. As Mittler3 found, sucrose formed the main constituent of the total solids and so for routine concentration measurements, a refractometer calibrated directly in percentage sucrose was used. The sugar content was analysed by paper chromato-graphy, the total nitrogen content measured using a micro-kjeldahl method4 and the individual amino-acids present detected by paper chromatography.

WHEN investigating the production of growth substances by Chlorella vulgaris var. viridis, difficulties were met which were ascribed to a growth-inhibiting substance, possibly Pratt's ‘chlorelline’1. Staphylococcus aureus proved to be a suitable test object for the growth inhibition. Small pieces of filter paper or agar slices containing concentrated and dried crude ether extracts of Chlorella were placed on agar plates seeded with bacteria. After 2–5 hr. of diffusion of the extract, and incubation of the bacteria at 37° C., clear inhibition zones were visible around the filter paper or agar slices.

IN Neptunea antiqua the salivary glands are large organs weighing 1–3 gm. (Fig. 1). The fresh glands have a peculiar intense smell, probably due to the presence of volatile amines. Extracts of the glands (made with water, acetone or ethanol) have a strong contracting effect on smooth muscle. When a dose corresponding to about 1 : 100 of a gland was injected into small fishes (Ctenolabrus, Gadus) or mice, the animals died within a few minutes. When somewhat smaller doses were injected intraperitoneally into mice, the animals survived but developed symptoms of heavy stimulation of the parasympathetic system : a profuse secretion of saliva and tears. The secretion could be abolished by atropine. Glandular extracts were tested on the heart of Cyprina 1 or the isolated radula-muscle of Buccinum 2 and were found to produce acetylcholine-like effects corresponding to a concentration of acetylcholine of about 10−5 gm./ml. Unlike acetylcholine solutions the extracts did not lose their physiological effects by short boiling at pH 9 or by the addition of acetylcholine esterase (a drop of human blood). Paper chromatography showed a very distinct spot which was stained brickred by dipicrylamine3 and had an R F-value between choline and acetylcholine. Sometimes it was difficult to distinguish this spot from a spot produced by choline. The spot could also be identified by exposure to iodine vapours or by pharmacological testing of strips of the filter paper.

THE last number of the Quarterly Journal of Microscopical Science has just come into my hands, containing a paper, by Mr. Beddard, on the nephridia of certain earthworms. In November of last year I read a paper, before the Royal Society of Victoria, on the anatomy of the large Gippsland earthworm, Megascolides australis. This, which reaches the length of 6 to 8 feet, is, I believe, the largest recorded earthworm, and its nephridial system is of great interest, corresponding closely in many points to that described by Mr. Beddard, in the above paper, as present in Acanthodrilus multiporus and Perichaeta aspergilium. My drawings have been for some time in the lithographers' hands, but as it will still be one or two months before the full paper is published, I should be glad to draw attention to the, in some ways, still more interesting features of the nephridial system in Megascolides australis. The nephridia are very evident, and can be divided clearly into two sets.

WE reported1 that some homogenates of Acacia georginae and of other plants can convert added inorganic fluoride to a volatile compound, which is lost after alkaline combustion. We found examples in which the total fluoride estimated by acid diffusion after combustion was less than the fluoride estimated by acid diffusion without combustion. The first hypothesis which we examined was that vinyl fluoride (CH2 = CH2.F) was formed. Some evidence (although not decisive) was obtained for this by gas chromatography using a column of ‘Poropak S’. We then explored the possibility that a volatile fluoroketone might be formed. Monofluoroacetone has been found in the livers of rats perfused with fluoroacetate2, and we record here evidence which suggests its presence as one of the volatile fluorine-containing constituents of the A. georginae homogenates.

SPERM cells of Paracentrotus lividus and Sphaerechinus granularis contain a quinone which shows the same chemical and physical properties as ubiquinone from the bovine heart. The method used for the extraction and purification of this invertebrate ubiquinone is quite similar to that used for the mammalian compound1. However, the presence in the extracts of a number of coloured substances, which have typical absorption spectra and which can undergo reversible oxidation-reduction, excluded the use of some common solvents, made column chromatography purification more difficult and restricted the use of the paper chromatography method and of the colorimetric test to the very purified material, that is, to its crystalline form only. It was impossible, therefore, to make any calculation of degree of purification during preparation and of the yield of the substance and of its original quantity. After several attempts the method was standardized as follows.

THAT glucose-cyclo-acetoacetate acts as a precursor of ascorbic acid in germinating green gram or mung beans (Phaseolus radiatus) has been shown by Nath and his associates1–3 and confirmed by the use of labelled glucose-cyclo-acetoacetate by Thangamani and Sarma4. Neither the titrometric indophenol dye method of Bessey and King5 nor the colorimetric method of Roe and Kuether6 is specific for L-ascorbic acid. We have therefore used paper chromatography to identify the additional reducing substance formed from glucose-cyclo-acetoacetate during the process of germination which decolorizes the indophenol dye, and find it to be L-ascorbic acid.

PREVIOUS studies have identified the 5′ terminus of several bacteriophage RNAs, including f2, as pppGp1–3. A number of other experiments using phage RNA and fragments derived therefrom as messenger in an in vitro amino-acid incorporating system have led to the suggestion that the viral coat protein is encoded near this 5′ end3–6. This interpretation depends on assumptions made about the translation of fragmented RNA or the causes of differential rates of protein synthesis from different cistrons in vitro.

PREVIOUS investigators1 have shown the presence of glycogenic activity, presumably of adrenal steroidal origin, in the plasma of the salmon (Salmo salar). An appreciable part of the activity could be accounted for by steroids reacting as 17-hydroxycorticoids by the Nelson–Samuels analytical method2. Since this technique measures a variety of materials having a dihydroxyacetone side-chain on the 17 carbon, the specificity of the determination is questionable in species of which the pattern of adrenal steroid secretion has not been established. Moreover, although cortisol (which is measured by the Nelson–Samuels method) is the chief steroid in the plasma of some mammals, in others the chief steroid, corticosterone, is not detectable by this method. This is especially important because Hatey found the concentration of glycogen-depositing activity to be much higher than could be accounted for by the 17-hydroxycorticosteroids1. The nature of the steroid responsible for a large part of the biological activity of salmon plasma remains uncertain. An attempt has therefore been made to determine the nature of the circulating steroids in fish blood by application of paper chromatography.

THE method described by Brieger and Cosslett1 of growing tubercle bacilli on the ‘Formvar’ film of a stainless steel electron microscope grid has been modified for use with liquid media. In this form the method has been found suitable for a study of the action of antibiotics upon growing tubercle bacilli. In order to prevent the fluid medium contaminating the inoculated surfaces, the grids are placed in contact with filter paper which rests on a cotton-wool support in a small dish 5 cm. in diameter and 2 cm. deep. The cotton-wool is kept moist by being thoroughly soaked in the medium. One dish can take up to twenty grids. The grids are inoculated with a drop of bacillary suspension using a fine platinum loop. If the drop does not stay on the surface of the grid, it is assumed that the holes in the ‘Formvar’ film are too large and the grid is discarded. The grids on which the drops remain are considered to be inoculated with similar numbers of bacilli. The dishes are incubated at 37.5° C. and grids removed at various intervals for inspection. Each grid is floated on sterile distilled water to remove any medium adhering to the lower surface, fixed by floating on 5 per cent formalin for 30 min., and washed again to remove any excess fixative. Throughout the procedure care is taken that the inoculated surface of the grid remains undisturbed. This is an essential condition for the study of variations in growth-rate.

PREVIOUSLY, we reported1 that fifteen honey samples produced mainly in the Tohoku region of Japan were analysed, and sugar components of one kind of honey (Lespedeza bicolor) were fractionated by chromatography, using a carbon : ‘Celite’ column, and the sugars in each fraction were estimated. Glucose, fructose, sucrose, maltose, melezitose, eight di- or tri-saccharides and nine higher oligosaccharides were detected by paper chromatography, and fifteen spots of them contained ketose.

Kaplan and Kaplan1 demonstrated that the addition of iodine to the alcohol used as a decolorizer in the Gram procedure resulted in retardation of the rate of decolorization. If the concentration of iodine was sufficiently high, no decolorization occurred. They also found that much higher concentrations of iodine in the alcohol were necessary to prevent the decolorization of Gram-negative bacteria than for Gram-positive bacteria. In their opinion these results indicated that differences in permeability to iodine in alcoholic solution contributed to the mechanism of Gram differentiation. In confirmation of the above work, Mittwer, Bartholomew and Kallman2 demonstrated that iodine in alcoholic solution stained Gram-negative cells much faster than Gram-positive cells. No such difference was demonstrable for iodine in aqueous solutions. The nature of the proof presented by the above workers, however, lacked accurate and objective results, and could not be considered as conclusive. When the methods of filter paper chromatography are applied to this problem, accurate and objective results can be obtained easily.

IN a Belgian patent1 granted to Spofa (Czechoslovakia) a number of pyrimidines chlorinated in the 2 position were reported to be active in inhibiting halogenation in the biosynthesis of chlortetracycline resulting instead in the production of high concentrations of tetracycline. It was of interest to us to test such compounds in the Streptomyces aureofaciens BC-41 system we have used before2. The two antibiotics were determined spectro-photometrically, taking advantage of their differential degradation rates in acid and alkaline solution. Compared with tetracycline, chlortetracycline is relatively stable to acid and unstable to base. Selected results were confirmed by paper chromatography. In the course of these trials, in which some thirty halogenated pyrimidines and related heterocycles were tested, very few were found to show activity. The most active compound was found to be 2,4-dichloro-5-methyl pyrimidine which, when added to the medium in a concentration of 10 p.p.m., resulted in the production of 80–95 per cent tetracycline in the final broth, confirming in part the work reported in the Belgian patent1. Closely related pyrimidines were either much less or not at all active for our strain BC-41. This is shown in Table 1.

Pearsall and Fogg1 have discussed the possibility of using algae, especially Chlorella, as a source of food. Though cultures having a very high protein content have been produced under suitable conditions of growth, little information is available regarding the amino-acid composition of such algal proteins. Eny2, using the technique of paper chromatography, reported that seven of the ‘essential’ amino-acids were absent from the proteins of Chlorella. These results are open to criticism on two grounds. The protein subjected to acid hydrolysis was apparently limited to that contained in an alcoholic extract of the Chlorella. This could only have been a small and probably unrepresentative fraction of the total protein. The anomaly that glutamine and asparagine were present after acid hydrolysis was also reported. A more detailed study of the amino-acids present in such algal proteins therefore seemed desirable as the first step of a proposed quantitative investigation.

THE nature and amounts of free amino-acids in higher plants are becoming relatively well known since the advent of paper chromatography. However, few investigations of amino-acids in the Cryptogams have been made. Fowden1 has studied the amino-acids of certain algae, Mansford and Raper2 those of Mucor mucedo, Fluck and Richle3 those of Fusarium lycopersici. The yeasts, Aspergillus, Penicillium and Neurospora species4, have been extensively studied but the rest of the fungi remain largely unexamined.

THE occurrence of 1,3-α linkage in some dextrans has already been suggested by many workers1–5. Barker et al.3,4 have fractionated the partial acid hydrolysate of the dextran produced by Betacoccus arabinosaseous (Birmingham strain) on a charcoal column and recognized the presence of a trace of nigerose by paper chromatography. Jeanes et al.5 have characterized dextrans from 96 strains of bacteria by periodate oxidation analysis and classified them into several groups on the basis of the proportions of 1,3 like linkages. According to their results, 29 of them appeared to contain more than 10 per cent 1,3 -linkages and a few of them showed an extremely high content of 1,3-linkages (more than 30 per cent).

WE wish to emphasize the usefulness of the method of paper chromatography of sugar1,2, especially when applied on a quantitative basis3, in the study of bacterial metabolism. As an example we quote the following experiment on the utilization of sucrose by Leuconostoc mesenteroides (Lister Institute strain No. 3351).

THE growth of autotropic unicellular organisms in purely inorganic medium is of great interest in biological studies. The production of amino-acids by such organisms is intimately connected with this growth. In the case of unicellular green algae, the production of amino-acids have been investigated by Fowden1, Pearsall and Fogg2 and Eny3. I have attempted to determine the free and bound amino-acids produced in the photosynthetic red sulphur bacteria using the technique of paper chromatography. These experiments also furnish a comparative study of the protein units of algae and photosynthetic bacteria.

IT was shown by paper chromatography that a cobalamin-producing strain of B. megaterium (N.C.I.B. No. 8508) gave a comparatively large amount of a new metabolite. This was a carbohydrate with RG 0.28 in butanol-water at 30°, reducing ammoniacal silver nitrate and giving a brown colour with aniline phthalate.

SELENIUM, long considered an element toxic to the majority of living organisms, may be of physiological importance in various animals as an indispensable part of the diet1–5. It may replace the sulphur atom in sulphur amino-acids6–14 in the proteins of plants, animals and micro-organisms15–18, and could stimulate cell division in a filamentous mutant of Candida albicans19. This stimulation has been related to the replacement of sulphydryl groups in the composition of the cell wall with —SeH groups, the greater stability of which can overcome in the filamentous mutant the deficiency in proteiin-disulphuro-reductase20, an enzyme indispensable to plastification of the cell wall21.

Arginine and Urea Biosynthesis in the Land Planarian: Its Significance in Biochemical Evolution

THE presence of a growth-inhibitory substance or substances in plant extracts, moving in paper chromatography with ammonical iso-propanol between R F 0.55 and 0.8 was first demonstrated by Bennet-Clark and Kefford1 who suggested the name inhibitor-β. These are now known to occur widely in plant material2,3, and according to Varga and Ferenczy2 the chromatographic behaviour is suggestive of a phenolic acid. Recently Bently4 reported that the inhibitor-β zone from potato peelings contained at least six components (possibly fatty acids) and that inhibition in Avena straight-growth assays was caused by toxicity at greater than normal physiological concentrations; shown by irreversability of the effect and by loss of turgor of the sections. One of these components was shown by Taylor5 to be azelaic acid.