224 ROBERT H. HUTCHISON 



2. The Paramecia from the acid medium were adversely 

 affected by M/4000 CaCl,, by M/lOO NaCl, and also by distilled 

 water. 



3. The conclusion is drawn that certain properties of the 

 medium in which the animals had been growing were the impor- 

 tant factors in determining the ability of Paramecium to with- 

 stand heat. No explanation is offered as to what these factors 

 are, nor how they act. 



4. The effects of continued exposure to moderately high tem- 

 peratures on the death temperature of Paramecium were studied. 

 Two cultures of Paramecia were kept in a water bath, the tem- 

 perature of which ranged from 28° to 36°C. The mean death 

 temperature of these two strains fluctuated considerably, and at 

 times was about 1° above the highest mean death temperature of 

 a control culture kept in a cool room. But this increase above the 

 control was not constant, and on the whole no very decided 

 effect was produced. 



