I. LIFE PROCESSES 



21 



data in tables 1 to 3 shows, to the fact that body-weight in- 

 crease during adult life tended to be greater in females than 

 in males as the generations advanced. The increased weight 

 of the females is to be attributed chiefly to the accumulation 

 of fat in the body tissues, not to growth of the body as a 



TABLE 3 



Showing the increase in the weight of the body with age for individuals in the 

 eighth to the tenth generation* of captive gray rats 



whole, since body length in females of the later ir -n. -rations 

 was no greater than that in females of the earlier generations 

 (table 12). Body growth of males during the second growth 

 phase was apparently less influenced by the favorable en- 

 vironmental and nutritive conditions under which tin- ani- 

 mals lived than was that of females. 



