472 



ON INCREASE IN SIZE AND WEIGHT [pt. iii 



short, but only 31-6 times as short. A mammal as small as a 

 gnat, therefore, would probably have a gestation period of 8 or 

 9 days. The explanation of this must lie in the time requirement of 

 differentiation. 



lOOOOpr 



1000 - 



100 - 



10 



TO 



0-1 



0-01 



0-05 0-1 



1-0 



10 

 Fig. 67. 



100 



1000 3000 



Another way of looking at the data appears in column 10 of Table 63 

 and in Fig. 67. In order to eliminate the factor of weight, the 

 gestation time in days per kilo of adult animal is calculated, and this 



