6 Female Families in Abraxas 



point of interest should be noticed — that in the unisexual families the 

 ordinary rules of sex-limited transmission are followed. A grossulariata 

 female, mated with a lacticolor male, normally produces lacticolor female 

 and grossulariata male offspring; if the family consists entirely of 

 females, these are all lacticolor, and the grossulariata character is not 

 transmitted at all (cf. families '07. 19, '11. 9 and '11. ^). 



It has been mentioned that a considerable proportion of matings of 

 females from unisexual families, especially when the male is related, are 

 infertile. In 1912 I dissected most of the females paired, after the 

 eggs were laid, in order to see whether the ovaries were in any case 

 abnormal. Although in three cases I have found ovaries containing no 

 oocytes in larvae dissected for histological examination, I found no 

 abnormal ovaries, with the exception of one which had six egg-tubes 

 instead of four, in the moths which had been paired. In several cases, 

 however, in which the eggs were infertile I found that the spermatheca 

 was nearly or quite empty, showing that copulation had not been 

 successful, but this cannot be the sole cause of the infertility, for in 

 other cases in which the eggs failed to develop the spermatheca was 

 well filled. 



Before passing on to the account of the cytology of the unisexual 

 families, it should be mentioned that my case of a hereditary tendency 

 to produce families consisting of females only appears to be closely 

 comparable with that discovered by Dr Lamborn in Acraea encedon, of 

 which a preliminary account has been published (Proc. Entom. Soc. 

 1911, p. liv). I hear from Prof Poulton that so far as the experiments 

 have gone at present, females from purely female families always have 

 only female offspring; those from bisexual families have both males 

 and females. If this is confirmed, it will show that the two cases are 

 not exactly similar. 



II. TJie Chromosomes in Unisexual families. 



In recent papers^ I have shown that the unreduced number of 

 chromosomes in both male and female of Abraxas grossulariata is 

 normally 56, and that there is no recognisable difference between the 

 type and var. lacticolor. In determining the chromosome number in 

 the oogonia of certain lacticolor females, however, I found several 

 perfectly clear figures in which only 55 could be counted, although in 



^ Journal of Genetics, i. 1911, p. 179, and ii. 1912, p. 189. 



