390 



HELEN DEAN KING 



THE EFFECTS OF SEMI-CASTRATION ON THE SEX RATIO OF 

 THE ALBINO RAT 



In February 1910, one testicle was removed from each of six 

 males, belonging to two different litters. One male, castrated 

 on the right side died before reaching maturity, so that two males 

 castrated on the right side and three males castrated on the left 

 side were available for the purposes of these experiments. Except 

 in the cases already noted, these males were mated with normal 

 females. The number of offspring produced, together with the 

 distribution of the sexes in the various litters, are shown in table 

 3. In this table the letters R and L refer to a castration on the 

 right or on the left side respectively. 



Table 3 



Practically equal proportions of the sexes were obtained as a 

 result of this series of experiments. The two males that were cas- 

 trated on the right side had a total of 35 offspring, of which 18 

 were males and 17 were females; the sexes were equally divided 

 among the 48 offspring of the three males from which the left 

 testicle had been removed. These results show that the sex 

 ratio was not affected by the removal of the right or of the left 

 testicle from the breeding males. 



In these experiments, as table 3 shows, the average number of 

 young in a litter was 4.88, which is very little higher than that 

 obtained in the former experiments (table 2). The records for 

 the litters produced by the semi-castrated males, as shown in 



