CHAP. II.] LABORATORY WORK ON GASTRIC DIGESTION. 



187 

 It is 



" 4. Rennet- Ferment. Use the pepsin-extract prepared in (1). 

 best to neutralise the milk employed. 



"Take (1) 5 c.c. extract + 5 c.c. of milk 



(2) + 2-5 +2-5 c.c. of water 



(3) + 1 +4 c.c. 



"Place at 39 C. The clot is firmer, and earlier formed the less diluted 

 the milk. 



"5. Rennet-Zymogen. Use the pepsinogen-extract prepared in 1. 

 With this repeat the experiments described under 4. 



"No clotting will take place until the fluid becomes acid from the con- 

 version of milk sugar to lactic acid. 



" 6. By experiments similar to those given for pepsin, it may be shewn 

 that rennet ferment is rapidly destroyed by Na 2 CO 3 , and that rennet- 

 zymogen is comparatively slowly destroyed by it." 



