42 THE PHYSIOLOGY OF PROTEIN METABOLISM 



nitrogen present was in the form of native protein and 67 per cent, in 

 that of peptone. In support of his work he quoted Gerlach and 

 Vogel (152) who stated that protein-forming bacteria were widely 

 distributed in nature (in the soil) and that if the conditions were suit- 

 able these bacteria acted rapidly and well. They found that nitrogen 

 in the form of nitrates was converted quantitatively into insoluble 

 protein in the presence of glucose. Ammonium salts could also under- 

 go the same change, but it proceeded at a slower rate. Miiller further 

 carried out a series of feeding experiments with this bacterial protein 

 which he prepared in sufficient amount and found that if it were added 

 to the diet of a dog it could entirely replace the ordinary protein 

 supply. Schulze (364) in a general discussion of this question holds 

 that this conversion of the amide into protein is probably correct. He 

 thinks the fact that ammonium acetate acts as well as the asparagine 

 strongly supports this contention. He does not come to any final 

 decision as to how the bacteria really bring about this synthesis. 



Much other work exists in favour of asparagine acting as a partial 

 substitute for protein, and it wotild seem that the form in which it is 

 given, plays quite an important part. Thus Lehmann (249) found that 

 he could obtain a greater protein sparing effect and even a retention 

 of nitrogen, if the asparagine were given embedded in celloidin, in order 

 to cause slow utilization, than if the asparagine were simply given free 

 in the food to the same animal. Miiller (293) confirmed this work. He 

 found that when the asparagine embedded in the celloidin was given to 

 dogs there was a retention of nitrogen in the body practically equal to 

 twice that found when asparagine was given free. He also stated that 

 if equal amounts of asparagine and serum albumin were given by this 

 celloidin method (the difference in caloric value between the two being 

 made up by means of carbohydrate), they acted equally well in bringing 

 about retention of nitrogen. Kellner (2 1 8), on the other hand, in his 

 experiments was quite unable to find any difference between the action 

 of free asparagine and asparagine embedded in celloidin. 



Voltz (4 1 3) and Voltz and Yakuwa (415) tested the effect on dogs 

 of the addition of different nitrogenous substances, ammonium acetate, 

 acetamide, glycine and asparagine and a mixture of all four, to a 

 ground ration consisting of meat, rice, lard and bones. They found 

 that there was no marked retention of nitrogen after the addition of 

 asparagine and that glycine was more or less indifferent in action. 

 Acetamide, on the other hand, caused a retention of nitrogen of about 

 O'2 grm. per diem, and ammonium acetate a retention of o - 4 grm. 

 nitrogen per diem. Munk (294) denied that asparagine could be even 



