240 



less under these circumstances, in proportion to the body weight 

 grows in a less degree than in the natural state. 



SO 



lOO 150 200 250 300 350 «CO 450 



Fig. 4. 



In 1918 I found an exponent of ^/ig = 0,27, i.e. of precisely 

 half the value of the exponent holding for the relative brain weights 

 froni species to species, on comparison of the volumes of largest, 

 i.e. of full-grown, homologous nerve or ganglion cells 

 in relation to the body weights of adult animals of very different 

 sizes, both of one species and of different species. Compare Tables I 

 and 11 '). 



Though in the microscopical image of the grey cortex the nerve 

 cells are placed as densely and are as unequal in size as the stars 

 in the telescopic image of the Milky Way, we may yet admit a 

 relation between the average size of these cells and the size of the 

 body, and look for the explanation of the relation holding for the 

 volume of the brain in the nerve cells, the elements from which 

 the brain is composed. 



The exponent holding between the adult individuals of one and 

 the same species, in the relation of the body weight to the brain 

 weight, may now be distinguished as ontogenetic exponent from 



1) These Proceedings, Vol. XX, p. 1328—1334. There too the fuller references 

 to the works of the authors mentioned in the last column of Table I. 



