No. 4.] 



THE DEVELOPMENT OF ANIMALS. 



i8 7 



subsisting entirely on its yolk supply during the time of the 

 measurements, therefore the factor of variable food supply is 

 eliminated. Thus the figures for growth in length of the tail 

 represent only the effect of the different temperatures, except- 

 ing naturally individual variations which are partially eliminated 

 by the averages. 



TABLE VII. Growth in length of frog tadpoles in 24 hours at different temperatures. 13.5 



units equal i mm. 



36 



24 



2O 



16 



12 



A 



1 



3 6 9 12 15 18 21 24 27 30 33 36 39 42 45 



FIG. 3. Curve of growth of the tail of frog tadpoles constructed from the above table. The 

 ordinates represent units (13.5 =-'1. i mm.) of growth and the abscissae degrees Centigrade. 



Comparison of the curves and of the tables shows that the 

 growth of the frog tadpole begins at a lower temperature than 



