165other of oat and grass hays, corn silage and a grain mixture. Ewes given the former ration produced lambs that developed muscular dystrophy, but the disease did not occur in lambs on the latter ration. The production of dystrophy was associated with a low tocopherolcontent of the ewes' milk, and Whiting et al." thought this was due to the low proportion of a-tocopherol in the clover, lucerne hays and beans. The analyses presented in Table I1 suggest that the so-called deficient diet probably contained more a-tocopherol than the other, since clover and lucerne contain a-tocopherol only, whereas the pand y-compounds form a large proportion of the tocopherols present in oats and maize. The contention of Whiting et al. therefore appears to be incorrect. The results of their experiment, however, emphasize the important interrelationship between vitamin E and other dietary factors.
Samples of ' collagen ' have been prepared from tendon dissected from shin of beef and found to have a maximum hydroxyproline content of 13-2%, giving a factor of 7-57 for converting hydroxyproline into ' collagen I . A comparison has been made of the results obtained for the ' collagen ' content of freeze-dried tendon preparations (a) by the hydroxyproline method and (b) by the modification of the Lowry, Gilligan & Katersky method previously published.Collagen fibres were originally identified by the histologist on the basis of their structure and staining reactions ; they were found to be the major components of many connective tissues. These fibres were later found to possess certain chemical properties, notably (i) dissolution and breakdown to gelatin on being heated with water, (ii) stability to certain enzymes, e.g. alkaline trypsin, which attack other proteins, and (iii) stability to certain chemical reagents, dilute acids and alkalis and salt solutions, which dissolve other proteins. More recently, the investigation of the structure of collagen fibres with the electron microscope and by X-ray-diffraction methods has revealed a common crystal lattice for collagen fibres from many sources but, as Bear1 has pointed out, such methods cannot establish chemical identity : ' -the situation is analogous to the phenomenon of isomorphism encountered in simple substances, wherein chemically similar but not identical species may replace one another in almost identical crystal lattices. In the collagens amino-acid residues may be presumed to be replaceable units within the fibrils which retain a basic type of organisation.'An initial difficulty in the establishment of collagen as a chemical entity is the insolubility of collagen fibres, from many sources, in water and in mild chemical reagents, but the recent work of Neuman & Logan,2 in which they found that ' collagen ' prepared from various materials was unique among proteins in having a high and fairly constant hydroxyproline content, indicates one line of attack on this problem.The preparation of samples of ' pure collagen ' has been described by a number of authors : (I) Highberger3 extracted the corium of cattle hide with alkaline trypsin ; the residue was washed, dried and ground to a powder. The powder was extracted with alcohol, freed from solvent and then extracted with half-saturated lime-water., Finally, the residue was washed successively with very dilute acetic acid and water, dehydrated with alcohol and ether and airdried.(2) Bergmann & Stein4 extracted Achilles tendon of cattle, comminuted by mincing it with solid CO,, with 10% sodium chloride solution followed by ~/15-disodium hydrogen phosphate solution.(3) Bowes & Kenten5 restricted the preparation of ' collagen ' from hide to extraction with 10% sodium chloride solution and removal of the grain layer and a thin layer on the flesh side, foIlowed by degreasing. They preferred to accept the presence of small amounts of elastic and reticular tissue rather than risk possible modification of the collagen...
be that the preliminary partial degradation of protein, carbohydrate and other constituents in the wilted material may make for quicker attainment of acid conditions in the silo, in which case total breakdown may be similar in both cases. Further experimental evidence is required before this question can be settled.Although silage and a slowly-dried crop show marked similarity in the extent of protein breakdown and in the resulting content of free amino-acid, there is one outstanding difference : in wilting there is a rapid accumulation of amides, particularly asparagine, ,whereas in silage the amide content is low and the ammonia content high. In the wilting crop, particularly under conditions of sustained moisture content, the cells remain alive for some time, there is little change in pH, and environmental conditions are suitable for the continued detoxification of ammonia by formation of the amides. It can be seen that the amide formed is much more than can be accounted for by freeing of amide residues from the protein molecule, in which about 574 of the nitrogen is amide-N. In silage, on the other hand, at least after the first day or so, conditions will be unsuitable for amide formation and the ammonia formed is not further metabolized, appearing as ammonium salts of organic acids.Rapid air-drying is carried out either in the field or in specially adapted barns with ventilated floors from which air, cold or warm, is driven through the mass. To furnish material which will be almost equal in biological value to the original crop, the drying must be as rapid as possible and the preliminary wilting which is often employed should in itself consist of a rapid removal of moisture. From a chemical point of view, the moderate raising of the temperature of the drying air, though hastening drying, may tend to catalyse a more rapid breakdown of protein, with no resultant improvement in the processed material. The higher cost may be offset by the quicker turnover of material. An indoor drying plant will obviate the risk of bad weather, but rapid drying in the field is probably the only method likely to compete economically with ensilage ; however, its value in this climate must always remain somewhat speculative. One practical difficulty with a small-leafed crop such as clover or lucerne is that the leaves dry out quickly and become brittle so that there may be considerable loss of the most valuable part of the plant when the dried crop is handled. With a grass, at least before it is in flower, there should be little loss from this source.Air-dried material is sometimes made as an alQrnative to silage. Acknowledgment Agricultural Research Council. This work forms part of a programme of research on crop conservation sponsored by the The principles of the available methods for determining collagen and elastin (as a measure of the connective tissue) in meat have becn examined. It has been shown that o.rh--NaOH is a more satisfactory reagent than either O'IN-or o.orh--HCl for leaching muscle tissue from connective tissue. W...
343yields of fat per IOO g. of carbohydrate utilized being : A . nidulans, from glucose 17.2 g., from sucrose x.3-2 g. ; P. spinulosum, from glucose 9.6 g., from sucrose 5.1 g. ; P . javanicum, from glucose 8.5 g., from sucrose 7.9 g. Experiments carried out recently in this Laboratory, but not yet published, have indicated that, with some moulds, fructose is less suitable than glucose as a source from which fat can be elaborated, and this finding may be related to the yields of fat from glucose and from sucrose that are cited above.
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