74 HELEN DEAN KING 



Tables 1 to 4 are inserted mainly for reference, but a compari- 

 son of the data for the males and females in the various genera- 

 tions brings out clearly the relation between the two sexes as 

 regards their relative body weights at different age periods. In 

 some few instances the average body weights of the males and 

 of the females in a given generation were the same when the 

 animals were thirteen or thirty days old, but after this age the 

 males were the heavier at each period for which records were 

 taken. A similar relation between the body weights of the sexes 

 was also noted for the inbred animals of the seventh to the 

 fifteenth generations (King, '18; tables 1 to 4). Investigations 

 in which large series of stock Albinos were weighed at stated 

 periods (Donaldson, '06; Jackson, '13; King, '15; Hoskins, '16) 

 have shown likewise that, with few exceptions, the average body 

 weight of the males exceeds that of the females at each weighing 

 period. Since the data for all generations of the inbred strain 

 is in full accord with that for various series of stock Albinos, it 

 is evident that inbreeding through twenty-five generations of 

 brother and sister matings has not changed the normal relative 

 body weights of the sexes at any age period for which records 

 have been taken. 



For the purpose of analysis and to facihtate a comparison 

 between the growth in body weight of the individuals in the 

 later generations of the inbred series with those in the earher 

 generations, the body-weight data for the animals belonging in 

 the sixteenth to the twenty-fourth generations of each inbred 

 series were combined in groups of three generations each: 

 the data thus combined are shown in tables 5 to 7. In each of 

 these tables the data for the individuals of the twenty-fifth 

 generation are given separately in order to show the status of 

 the animals at the end of this period of inbreeding. 



Data indicating the growth in body weight of males and of 

 females belonging in the various generation groups of the A 

 series of inbreds are shown in table 5. 



As a graphic representation of series of data greatly facili- 

 tates their comparison, the body-weight data for various groups 

 of albino rats, given in tables 5 to 11, have formed the basis 



