216 



ROBERT H. HUTCHISON 



The tables show that in this race the solution of M/3000 

 CaCl2 has raised the mean of the fatal temperature zone 1.68°C. 

 This is very nearly the same as the effect of M/50 NaCl, as 

 shown in table 2. The most pronounced effect was produced 

 by the addition of a little CaClo to the solution of NaCl. In 

 this case the mean was raised 2.26°C. The significance of these 

 increases is all the more important when one notices that the 

 means of the control experiments are almost exactly the same in 

 all the tests, although they were made at very different periods 

 in the history of the culture. 



The effect of KNO3 on this race of Paramecium is summarized 

 in table 5. 



The mean death temperature of this race was 1.9°C. higher in 

 M/50 KNO3 than in the corresponding controls. In three ex- 

 periments with M/lOO KNO3 the mean was found to be 41.1°, 

 a rise of 0.3°C. above the corresponding controls, which gave a 

 mean of 40.8°C. 



TABLE 5 



The effect of M/50 KNOz on the heat resistance of P. caudatum from an alkaline 



medium 



IN M/50 KNO3: SUM OF FIVE 

 EXPERIMENTS 



Totals subjected to each tem- 

 perature 



Number of deaths 



Percentage dead at given tem- 

 perature 



IN controls: sum of five 



EXPERIMENTS 



Totals subjected to each tem- 

 perature 



Number of deaths 



Percentage dead at given tem- 

 perature 



295 

 



224 

 



781 

 



380 

 



TEMPERATURES 



29° 40 



634 

 



584 

 221 



39.5 



623 



27 



4.3 



677 

 500 



73.8 



735 

 190 



723 

 723 



100 



694 

 210 



30.2 



725 

 725 



100 



691 

 691 



100 



MEANS OF THE ABOVE FATAL / in M/50 KNO3 41 .4° 



TEMPERATURE ZONES \ in controls 39.5° 



