226 



THE EFFECT OF TEMPERATURE 



stage of disappearance of the yolk plug was determined, 

 these being the most sharply marked periods. The 

 temperatures varied between 4 and 26 C., several ob- 

 servations being made at each temperature, and means 

 taken. 



From tbe above table we may gather that at the 



24 23 22 21 2019 181716 15 1413 12''ll' > 10 9' > 8 7 6 5 4 3 2 1 



I?IG. 22. Effect of temperature on growth of tadpole. 



highest temperatures employed the rate of develop- 

 ment was respectively 7.2 and 21.9 times more rapid 

 than at the lowest. 



In the accompanying figure are reproduced the re- 



