RENNIN AND PEPSIN 43 



In some cases the extract from young rabbits' stomachs was incubated 

 with acid and fibrin for 18 hours without any appreciable amount of digestion 

 taking place. 



At the end of every coagulation experiment, in the case of the adult 

 extracts, a few drops of active rennin were added to the mixture of extract + 

 milk. Coagulation now always took place, proving, if need be, that the absence 

 of coagulation at first was not due to lack of calcium or other deficiency in 

 the milk, but to lack of rennin in the extract. These facts, so far as they go, 

 seem to argue against pepsin and rennin being identical. The extracts were 

 exactly similar in mode of preparation and it is unlikely that one set would 

 contain any inhibitory substance (for example removable by dialysis) which 

 would be absent from the other. No stomach, either of young or adult rabbit, 

 was an exception to the rule that in young animals we get rennin but no 

 pepsin, and as the animal reaches adult life the rennin entirely disappears 

 but pepsin is now found in the stomach. 



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Gewin (1907). Zeitsch. physiol. Chem. 54, 32. 



Gmelin (1902). Pflvger\s Arch. 90, .591. 



Hammarsten (1908). Zeitsch. physiol. Ghem. 56, 18. 



Nencki and Sieber (1901). Zeitsch. physiol. Chem. 32, 291. 



Oppenheimer (1913). Die Fermente und ihre Wirkungen, 4te Auflage. 



Pavlov and Parastschuk (1904). Zeitsch. physiol. Chem. 42, 415. 



Porter (1911). J. Physiol. 42, 389. 



Rakoczy (1910). Zeitsch. physiol. Chem. 68, 421. 



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