New York Agricultural Experiment Station. 211 



enzyme and pepsin agree closely when working" on the same 

 material under comparable conditions; (c) the classes of soluble 

 nitrogen compounds formed by the two enzymes are the same 

 both qualitatively and quantitatively; (d) neither enzyme forms 

 any considerable amount of amido compounds, and neither pro- 

 duces any ammonia; (e) the soluble nitrogen compounds formed 

 by either enzyme are chiefly confined to the groups of com- 

 pounds known as paranuclein, caseoses and peptones. 



(6) The experiments made to determine the influence of salt 

 on the proteolytic action of rennet-enzyme, while not conclusive, 

 suggest that salt has little or no effect upon the action of rennet- 

 enzyme in cheese-ripening. 



(7) In obtaining our results relating to the study of the func- 

 tion of rennet-enzyme in cheese-ripening, we were necessarily 

 compelled tO' work imder conditions more or less abnormal as 

 compared with the conditions commonly present in cheese- 

 making. The effect of such unusual conditions would tend, if 

 they had influence at all, to diminish the proteolytic action of 

 rennet-enzyme. We are, therefore, justified in believing that our 

 results represent the minimum effect of rennet-enzyme in cheese- 

 ripening and that, under normal conditions, it takes, if anything, 

 a larger part than that indicated by our experiments. 



(8) In some experiments, we eliminated all milk-enzymes and 

 all active forms of organisms contained in the milk before making 

 it into cheese. In some cases, we had rennet-enzyme in the 

 presence of acid as the only proteolytic agent in the cheese; in 

 others, we had the same conditions and, in addition, such pro- 

 teolytic organisms as chanced to get into the milk and curd dur- 

 ing the process of cheese-making. In the latter case (52 and 53), 

 larger amounts of amides were formed, and some ammonia; while, 

 in the presence of rennet-enzyme alone, no ammonia was formed 

 and only small amounts of amido compounds. When we com- 

 pare normal cheese with cheese containing only rennet-enzyme, 

 we find the same difference, except that it is more pronounced, 

 as we should expect. Hence, the special work done by the 

 rennet-enzyme as a factor in cheese-ripening is that of a peptic 

 digestion, forming groups of water-soluble nitrogen compounds, 

 intermediate in complexity of structure between paracasein and 

 the amido compounds, viz., paranuclein, caseoses and peptones. 



