18 



HELEN DEAN KING 



represent the adult body size of the progenitors of the animals 

 whose growth is indicated by graph A, since rarely do we find a 

 group of mammals having in the adult state a body size so much 

 greater than that of its immediate ancestors. 



d 20' 40 60 80 166 120 U6 160 \a6 200 220 240 26O 280 3C0 320 340 360 380 400 420 440 460 480 



Fig. 2 Graphs showing the increase in the weight of the body with age for 

 males belonging to various generation groups of the A series of inbreds (data in 

 table 1 and in table 8). A, graph for males of the seventh to the ninth genera- 

 tions inclusive; B, graph for the males of the tenth to the twelfth generation in- 

 clusive; C, graph for the males of the thirteenth to the fifteenth generations 

 inclusive; D, graph for the males of the first six inbred generations. 



Graphs showing the growth in body weight of females belong- 

 ing to the three generation groups of the A series are shown in 

 figure 3 (data in table 1 and in table 8). 



The females of the first six generations of the A series were 

 very much smaller than the females of the later generations at 

 every age for which records were taken, as the position of graph 

 D in figure 3 clearly shows. There was practically no difference 

 in the rate or in the extent of the body growth in the groups 



