246 T. BRAILSFORU ROBERTSON. 



21, 21, 29, 27, 25, *2i, 19, 17, 15, 1 1-- hence the 

 rate of beat at 21 was counted three times, twice at the begin- 

 ning of the experiment and once after taking the animal through 

 a series of temperature-changes none of which were extreme 

 it will be observed that the three observations at 21 are in very 



good agreement. 



EXPERIMENT 8. 



Temperature. Beats per Second. 



11 1.82 



15 2 -95 



17 3-78 



19 4-09 



*2i 4-375 



21 4-151 . 



> Average = 4.40 



21 4-65 ' 



25 4.67 



27 6.67 



Average rate at 21 Rate at 25 



Rate at 11 ' 4I ' Rate at i 5 



Rate at 27 



Rate at 1 7 



= 1.76. 



The beat was regular throughout the experiment. The organ- 

 ism was taken through the following temperatures in the follow- 

 ing order: 21, 21, 29 (beats not counted), 27, 25, *2i, 

 19, 17, 15, 11 hence the rate of beat at 21 was counted 

 three times, twice at the beginning of the experiment and once 

 after taking the animal through a cycle of temperature-changes 

 none of which were extreme the three determinations of the 

 rate at 21 are in good agreement with each other and with 

 those in experiment 7. 



EXPERIMENT 9. 



Temperature. Beats per Second. 



19 3-2? 



21 5-12 



29 6.25 



The organism was taken through the following temperatures 

 in the following order, 31 (not counted), 29, 21 and 19. 



Rate at 29 

 Rate at 19 = 



