ZOOLOGY, ENTOMOLOGY, AND MEDICINE 



251 



These two experiments show, as has been recognized for a 

 long time, that living cells are very resistant to the action of 

 proteolytic enzymes, while dead cells are digested with more 

 or less ease. 



The digestive strength of the trypsin and the resistance of 

 the living paramecia having been determined by these control 

 experiments, an attempt was made to lower the resistance of 

 the organisms to tryptic activity by decreasing their oxidate 

 processes. Five c.c. of the activated dialyzed pancreatic juice 

 were exposed to the radiation from a quartz mercury-vapor 

 burner for one hour to destroy the trypsin. Living paramecia 

 were introduced into this inactive juice, and hydrogen gas 

 was bubbled through it for ten hours at 30° C. The purpose 

 of bubbling the hydrogen gas through the juice was to deprive 

 the paramecia of most of the oxygen dissolved in the liquid 

 and thus decrease the oxidative processes of the paramecia. 



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v I 



At the end of the ten hours the organisms were alive and 

 active. This experiment shows that the hydrogen gas bubbled 

 through the liquid was not injurious to the paramecia and 

 that there remained in the liquid sufficient oxygen for the life 

 processes of the organisms. 



Five drops of water containing paramecia were introduced 

 into 5 c.c. of the activated dialyzed pancreatic juice. Hydro- 

 gen gas was bubbled through this liquid as it had been through 



