CHEESE MAKIKG. 359 



tions for twelve months before using them, in the belief 

 that they gain strength during this period and then yield 

 the best and strongest rennet. When used, the various 

 dried preparations are steeped in water or whey, the 

 infusion being saturated with salt, and this liquid is 

 bottled and kept for two months before it is made use 

 of. In some places the stomachs thus steeped are dried 

 and salted and used a second or even a third time, after a 

 period of rest, and it is possible so to use the stomach re- 

 peatedly for an indefinite period. The question then 

 occurs. By what means does the rennet effect the coagu- 

 lation of the milk ? 



Rennet is a digestive agent. In the process of diges- 

 tion of milk the gastric juice which is secreted by the 

 stomach is always acid; and it contains a considerable 

 proportion of lactic acid as well as of hydrochloric acid. 

 The cells of the stomach known as the peptic cells secrete 

 this fluid, which contains in addition to the acids a small 

 quantity of an albuminous compound known as pepsine, 

 and this substance is supposed to be chiefly concerned 

 in the digestion of albuminoid portions of the food. 

 Then we must believe that the coagulating property of 

 rennet is a true digestive function, and that the liquid 

 rennet is really an artificial gastric fluid. We know 

 further that the ripening of cheese is really a digestive 

 process, and the well-ripened cheese is used as an aid to ■ 

 digestion ; proving that the influence of the rennet is 

 carried into and shared with it by the cheese. But 

 whatever may be the hidden secret — as yet undiscovered 



we cannot free our mind from the conviction that the 



coagulation of the milk, and the production of curd, are 

 really due to the action of lactic acid produced in the 

 milk by the rennet. 



Then the question arises, Why does milk curdle so 

 much more quickly under the influence of rennet than 

 by the ordinary process of souring ? This more effective 



