The effects of semi-spaying and of semi-castration on the sex ratio of the albino rat (Mus norvegicus albinus) / Helen Dean King.

  • King, Helen Dean, 1869-1955.
Date:
1911
Catalogue details

Licence: In copyright

Credit: The effects of semi-spaying and of semi-castration on the sex ratio of the albino rat (Mus norvegicus albinus) / Helen Dean King. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    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 MALE NUMBER NUMBER OF LITTERS NUMBFR OF YOUNG AVERAGE NUMBER YOUNG PER LITTER MALES FEMALES i(R) 4 17 4.1 10 7 2 (R) 4 18 4.2 8 10 3 (L) 2 14 7.0 9 5 4 (L) 4 21 5.2 9 12 5 (L) 3 13 4.3 6 7 17 83 1 4.88 42 41 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