FOODS NUTRITION. 1105 



has to do with the relation of digestive ferments and micro-organisms to the energy 

 balance of the body. 



The source of muscular energy, A. Tkunz (Fuhling's Landw. Ztg., 53 (1904), 

 Nos. 21, pp. 785-790; 22, pp. 838-843). — A critical summary and discussion. 



The general conclusion is drawn that protein, fat, and carbohydrates may all be 

 sources of muscular energy. So long as nitrogen-free nutrients are supplied in abun- 

 dance in the food or stored in abundance in the tissues they are used for muscular 

 work. When they are no longer present protein is a source of muscular energy. 

 Furthermore, it appears that the muscles utilize for muscular work not only the 

 energy due to cleavage of nutrients, but also, owing to its affinity for the cleavage 

 products, the oxygen which is present in muscles. 



The way in which chemical energy is converted into muscular energy in the mus- 

 cles is not definitely known. When more food is supplied than is required for main- 

 tenance only 33 per cent of the energy of the excess food materials, on an average, is 

 converted into muscular work in the case of farm animals. 



Gelatin as a substitute for proteid in the food, J. R. Murlin (Science, n. ser., 

 21 (1905), No. 525, pp. 106, 107). — At the December meeting of the New York Soci- 

 ety for Experimental Biology and Medicine, the author reported the results of 

 experiments on gelatin as a substitute for protein in food. 



In tests with dogs, amounts of gelatin furnishing from one-fourth to two-thirds of 

 the nitrogen required were fed, the remainder of the nitrogen being supplied by 

 meat proteid. The rations were so arranged that the energy requirements were fully 

 met by fats and carbohydrates. The protection of body protein was the same when 

 one-fourth, one-third, and one-half of the nitrogen of the food were supplied by gel- 

 atin, the coincident protecting power of fats and carbohydrates being the same. 



When the coincident protecting power of nonproteid food is increased by feeding 

 larger percentages of carbohydrates and less fat, the author states that two-thirds of 

 the nitrogen requirement of the body may be met by gelatin and nitrogen equilibrium 

 maintained at the starvation level. The results were confirmed, it is said, in experi- 

 ments with man. 



The physiological effects of peptone and allied products. VI, The metab- 

 olism of arginin, W. II. Thompson (Jour. Physiol., 32 (1905), No. 2, pp. 137- 

 146). — In experiments with dogs it was found that arginin fed as chlorid or carbonate 

 caused an increase of nitrogen in the urine. The greater part of the nitrogen, 72.8 to 

 96.3 per cent, appeared as urea. 



In laboratory tests only half the nitrogen was obtained as urea, the other half 

 being obtained as ornithin. In the animal body either ornithin is not formed, or if 

 formed is reconverted for the most part into urea. Much the same effects were 

 obtained when arginin was administered by hypodermic injection, except that more 

 nitrogen was excreted in the urine than could have come from the arginin given. 

 The excess of nitrogen did not appear to be caused by the solvent employed, conse- 

 quently one must assume, according to the author, that arginin stimulates nitrog- 

 enous metabolism. 



The nutritive value of the cleavage products of albumin. I, The energy 

 involved in digesting meat and somatose, W. Cronheim (Arch. Physiol. [Pflii- 

 ger~\, 106 (1904), No. 1-2, pp. 17-42, dgms. 2). — From experiments in which the res- 

 piratory quotient was determined the author concludes that as much as 30 gm. of 

 somatose can be taken without causing digestive disturbances, and that this quantity 

 is digested with less labor than an equivalent amount of meat. 



On the relation of enterokinase to trypsin, W. M. Bayliss and E. H. Star- 

 ling (Jour. Physiol., 32 (1905), No. 2, pp. 129-136). — The following is quoted from 

 the author's conclusions based on experimental work: 



"There is no evidence that a solution of trypsin is equivalent to a combination of 

 kinase and trypsinogen. Trypsin is a new substance, differing from trypsinogen, and 



