ABDERHALDEN'S EXPERIMENTS 65 



not only in a qualitative but also in a quantitative sense. 

 Experiments of E. Voit and Zisterer, 51 in which the matter 

 of "economy" comes forward, apparently bear upon this 

 point, uncleft casein being superior to digested casein and 

 the latter superior to casein hydrolyzed by acid. With ad- 

 vance of cleavage the physiological nutritive value of a sub- 

 stance apparently decreases, larger and larger amounts at 

 any rate being required for maintenance of nitrogen balance. 

 On the other hand a recent series of experiments by Abder- 

 halden, Frank and Schittenhelm would indicate that protein 

 equivalence of the combined cleavage products is a complete 

 one. Acquiescence may be granted to the first of these in- 

 vestigators only in the sense that positive results in such 

 experiments are always of more significance than are nega- 

 tive ones. Experiments carried on by Buglia 52 in Botazzi's 

 laboratory clearly confirm the view that the products of 

 meat digestion can be substituted for the meat itself without 

 noteworthy difference of result in nitrogen fixation and in- 

 crease of body weight in growing animals. 



Finally Abderhalden in a very interesting experiment 

 has fed animals upon a general diet, not merely proteid sub- 

 stances, in state of complete cleavage. Dogs were given, be- 

 sides the fully split protein, the cleavage products of fat 

 (glycerol and the higher fatty acids), monosaccharids, 

 cholesterol, the structural units of nucleinic acid and the 

 necessary ash constituents. In the course of experiments 

 extending over more than two months the experiment ani- 

 mals not only maintained their nitrogen equilibrium but 

 actually increased in weight. 



This is an example of indefatigable and purposeful labor 

 ending in the solution of a great problem. If one reflects, 



81 E. Voit and J. Zisterer (Veterinary School, Munich), Zeitschr. f. Biol., 

 53, 457, 1910. 



62 G. Buglia (F. Bottazi's Lab., Naples), Zeitschr. f. Biol., 57, 365, 1911. 



5 



