260 ILLINOIS ACADEMY OF SCIENCE 



lOOMin 



5 10 15 20 30 40 *C 



Fig. 1. Curves of the development of the frog's egg at different 

 temperatures. The curve AB is the time temperature curve for de- 

 velopment of the first cleavage plane. The curve A'B' is the reciprocal 



1 



of the time temperature curve, i. e. the plotted on 



Time in minutes 

 the temperatures in question. The distance above the axis of tempera- 

 tures represents relative velocity of development. 



