206 EXPERIMENT STATION RECORD. 



enzyms in a relatively pure state. Their number and character have not 

 been studied in detail, but they were found to be more closely allied to 

 the tryptic than to the peptic class. When the extracts were added to 

 milk and cheese they hastened the breaking down of the casein. Finally, 

 cheese was made from milk which was kept under chloroform to pre- 

 clude the action of bacteria, and the same cheese was kept in a satu- 

 rated atmosphere of chloroform for a long period to observe the ripen- 

 ing. Under these conditions bacteriological growth was impossible, 

 but the cheese ripened as fast as normal cheese kept under favorable 

 conditions. It appears, therefore, that as far as the peptonizing of the 

 casein is coucerned by far the larger part of it is due to the action of 

 unorganized ferments which occur normally in milk rather than to the 

 action of bacteria. 



The reasons why other investigators have failed to find these sub- 

 stances is because they have adhered too closely to the usual bacteri- 

 ological methods. For instance, they have usually worked with milk 

 sterilized by means of heat alone, and then planted in the sterile milk 

 cultures of various organisms in order to determine their peptonizing 

 effect. In this way they have eliminated the action of these inherent 

 enzyms. It was not until antiseptics were employed for sterilizing that 

 the keystone to the whole question was discovered. 



In this connection some entirely independent experiments recently 

 reported by Jensen in Denmark, noted in this number, are especially 

 interesting. He made experiments in ripening cheese with the aid of 

 trypsin. Pasteurized milk was used, and a preparation of pancreas 

 was kneaded into the cheese curd before putting it to press. As a 

 result of this work Jensen concludes that the ripening of cheese is 

 largely due to the action of an enzym (casease) very similar to trypsin, 

 but he adduces no evidence to show the occurrence of such an enzym 

 in normal milk or to explain its presence in cheese curd. 



Drs. Babcock and Russell have definitely proved the occurrence of 

 enzyms in milk and their causal relation to the ripening of cheese, and 

 have thus added one of the most important contributions of biological 

 chemistry to agriculture from both a scientific and a practical stand- 

 point. 



