MICRO-ORGANISMS AND ENZYMS 297 



widely distributed and are common in milk. The con- 

 ditions usually present in milk are not favorable to 

 their growth and they are not, therefore, the source 

 of trouble so often as are bacteria. Among the effects 

 which can be attributed to the action of different 

 yeasts are the formation of bitter and of fruity flavors 

 (pp. 118, 126). 



MILK-ENZYMS 



Milk contains several different enzyms. Some of 

 them, at least, are of bacterial origin. It would take 

 us too far from the purpose of this discussion to go 

 into details relating to milk-enzyms. We shall con- 

 fine our attention to the one known as galactase. In 

 1897, Babcock and Russell announced the discovery 

 of an unorganized ferment or enzym in milk to which 

 they gave the name of galactase. They were led to 

 this discovery by observing that fresh milk coagu- 

 lates, even when obtained as free as possible from 

 bacteria, and when all bacterial activity has been 

 stopped by treatment with ether or chloroform. The 

 milk first coagulates and then the curd gradually dis- 

 solves. Having excluded the seeming possibility of 

 bacterial action in the milk after it was drawn, they 

 concluded that the observed coagulating and dissolv- 

 ing action must be due to enzym action, probably two 

 different enzyms. Galactase is probably a mixture 

 of two or more different enzyms, since it has 

 been shown that separator-slime, when treated accord- 

 ing to Babcock and Russell's method in preparing 

 galactase contains at least three distinct enzyms, 

 galactase proper, peroxidase and catalase. The dis- 

 tinctive feature of the action of galactase is its powei 



