THE DEVELOPMENT OF THE FROG'S EGG 333 



Effect of Heat and Light on Development. Eggs devel- 

 oping in normal environments in nature arrive at nearly 

 the same end-result even when the environments are not 



J848 

 MARCH 1lTfi 



20J.H 

 230 

 25TH 



27TH 



28TH 

 31ST 



APRIL 4TH 

 6TH 



10TM 

 MAY 22D 



AUG. 18T.H 



28TH 



OCT. 3 1ST 



60FAHR. 



ft 



MEAN TEMPERATURE 



56FAHR. 



53FAHR. 



51FAHR.. 



9 



FIG. J306. A chart showing the correlation between the stage of development 

 of the frog on successive days and the temperature at which it has de- 

 veloped. From Higgenhottom. 



identical. We gain, in consequence, an impression that 

 development proceeds unaffected by any changes in the 

 outside world. But this is not true. For one thing, the 



