76 



HELEN DEAN KING 



for the construction of the graphs shown in figures 1 to 8. The 

 graphs in figure 1 show the growth in body weight of four gener- 

 ation groups of male rats belonging in the A series of inbreds 

 (data in table 5). In this, as in some of the other figures, the 

 graphs should properly run very close together or overlap in 

 various places. If, however, the graphs had been drawn in this 

 manner, it would be difficult to follow their course, and therefore 



Showing the average body weights at different ages of inbred rats of the A series, 



separated into groups according to the generation to which the 



individuals belonged 



the space between them has been arbitrarily widened in some 

 places in order to keep the lines distinct. 



While the general course of all of the graphs in figure 1 is much 

 the same, their relative position clearly shows the progressive 

 decrease in body weight that has resulted from the action of 

 unfavorable conditions of environment and of nutrition. The 

 rats in the sixteenth to the eighteenth generations were fed, for 

 the most part, on 'scrap' food, and, as graph A in figure 1 shows, 



