190 PROTEINS AND CARBOHYDRATES 
bacteria could not start the decomposition of the proteins. Rettger, 
Berman and Sturges (1916) have continued this work and reported that 
proteoses and peptones follow essentially the same law of resistance to 
bacterial action as do the native proteins. They found that if there 
was sufficient nitrogen in other combinations to allow growth of the 
bacteria in order that proteoses could be secreted, the proteins were 
hydrolyzed. When no growth took place due to the lack of available 
nitrogen, no hydrolysis occurred. The bacteria used in the above 
experiment might be regarded as “ starved ”’ and thus not in a normal 
condition. Robinson and Tartar (1917) when studying this question 
made no attempts to use purified proteins: blood fibrin, egg albumin, 
casein, gliadin and peptone were split by bacteria to ammonia. The 
chief source of ammonia seemed to be the monoamino and diamino 
nitrogen. The work of these investigators simulates more closely the 
conditions in our common media and in nature. 
Action of Bacteria on Polypeptids. Sasaki (1912) reported the 
B. colt split glycyl-l-tyrosin and glycylglycine into their component 
acids and from this they conclude that bacteria probably plays a réle in 
digestion. ‘The same author in two other papers reports investigations 
wherein liquefying and non-liquefying bacteria were used. With non- 
liquefying types such as typhi, dysentery, etc., glycyl-l-tyrosine and 
glycylglycine were decomposed to their component acids. Sasaki 
regards this change as due to an ereptase-like enzyme, excluding pep- 
tase because synthetic polypeptids were used. ‘The various liquefying 
bacteria which he used were also able to split the polypeptids. In 1914 
Sasaki killed B. cold with toluene and, after action on polypeptids, 
demonstrated that they were split into their amino acids. Somewhat 
similar results have been reported by Mito (1918). He tested the 
enzymes of B. coli communis and Staph. aureus on di-leucylyblycine. 
Asymetric cleavages were secured. The copper salt of l-leucine was 
isolated. The mother liquor exhibited an optical activity compatible 
with d-leucylglycine. Sasaki (1917) grew B. colt communis and B. 
proteus vulgaris in tyrosine containing media of two kinds. One of these 
media contained lactose to allow acid formation while the other con- 
tained a mixture of phosphates to maintain neutrality. In the lactose 
media both bacteria formed p-hydroxyphenyl-ethylamin. In the lac- 
tose free media no amine could be isolated but rather large amounts of 
d-p-hydroxyphenyllactic acid were secured. 
Bacterial Action on Other Bodies Related to Proteins. There exist 
a class of compounds which stand between the carbohydrates and pro- 
teins—glucosamin, 
