Volume IV JUNE, 1914 No. 1 



ON THE RELATIONS BETWEEN CHROMOSOMES, 

 SEX-LIMITED TRANSMISSION AND SEX- 

 DETERMINATION IN ABRAXAS GROSSU- 

 LARIATA. 



By L. DONCASTER, Sc.D., 

 Fellow of King's College, Cambridge. 



In the last of a series of papers on chromosomes and sex in 

 Abraxas grossulariata (Currant Moth), I described breeding experi- 

 ments with a strain which in each generation produced families 

 consisting entirely of females, and showed that in this strain all 

 the ovaries examined, with one exception, had oogcmia with 55 chro- 

 mosomes instead of 56, the normal number in the species'. The 

 present paper confirms and amplifies the results previously described, 

 gives an account of the chi-omosomes in the maturation of the egg 

 in normal females and in the strain which produces unisexual broods, 

 and describes an exception to the normal sex-limited transmission of 

 the grossulariata character which can possibly be correlated with an 

 exception in the chromosome number in such a way as to suggest 

 a definite relation between that character and a chromosome. It 

 also gives direct evidence of dimorphism of the eggs in respect of 

 chromosome number, exactly comparable with the dimorphism of sper- 

 matozoa which has now been described in so many insects of other 

 orders. 



Material and Methods. 



The methods adopted were in general the same as described in 

 my previous papers, except that the larvae (usually about half-grown) 

 were dissected in most cases in tap-water instead of Ringer'.s fluid. 

 I found by accident that this gave clearer division-figures ; I discovered 

 that the Ringer's fluid used for the ovaries obtained in the autumn 



' Journal of Genetics, VoL in. 1913, p. 1. 

 Journ. of Gen. iv 1 



