EFFECTS OF INBREEDING ON BODY WEIGHT 



77 



the males of the A series that belonged to these generations were 

 heavier at all ages than were the males in the later generation 

 groups, excepting at the 243-day period. Rats in the nineteenth 

 to the twenty-first generations were not greatly affected by the 

 change in diet, as for some months it was possible to give them 

 'scrap' food part of the time. The males of this generation 



Fig. 1 Graphs showing the increase in the weight of the body with age formales 

 belonging to various generation groups of the A series of inbred rats. A, graph 

 for males of the sixteenth to the eighteenth generations, inclusive; B, graph 

 for males of the nineteenth to the twenty-first generations, inclusive; C, graph 

 for males of the twenty-second to the twenty-fourth generations, inclusive; D, 

 graph for males of the twenty-fifth generation (data in table 5). 



group, as the position of graph B indicates, were nearly as large 

 as were those of the earher generation group during the adoles- 

 cent period, but in the adult state their body weights fell off 

 rapidly. Individals in the twenty-second to the twenty-fifth 

 generations of the inbred strain suffered most severely from the 

 altered food conditions as well as from extremes of temperature, 

 and the males of the A series were very inferior in body weight 



