RESEARCHES ON THE SEX-CHROMOSOMES OF 

 PSYCHICS (LEPIDOPTERA). 



J. SEILER. 



WITH ONE TEXT-FIGURE AND ONE PLATE. 



The demonstration which I have given of the digametic condi- 

 tion of the female sex in Lepidoptera in the case of Phragmatobia, 1 

 gave a brilliant confirmation of the assumption made by genetic 

 experimenters (Doncaster, Goldschmidt) that in butterflies the 

 female sex must be digametic. In all other cases the digametic 

 condition has been conclusively demonstrated only in the male, 

 and as was to be expected, therefore, my results were doubted. 

 For this reason I sought for a typical case in which the distri- 

 bution of the sex-chromosomes could readily be demonstrated, 

 and to work it out in such a manner as to leave no room for further 

 doubt. 



Such a typical case was found in certain species of Psychidae. 

 I was led to examine this group because the sex-ratios (which 

 under certain conditions are quite atypical) gave reason to 

 look for interesting cytological conditions; for it might be 

 expected that in the parthenogenetic species, as is the case in 

 Angiostomum, Phylloxera, etc., the preponderance or exclusive 

 appearance of only one sex might be determined by the sex- 

 chromosome mechanism. Unfortunately this point could not 

 be demonstrated; on the other hand, the dioecious forms, Talce- 

 poria tubulosa and Fumea casta, were found to offer material 

 suitable for my main purpose. 



i. Talceporia tubulosa RETZ. 



(a) Maturation of the Egg. As the daughter-chromosomes of 

 the first maturation-division separate, one chromosome remains 

 at the middle of the spindle without showing at first any indica- 

 tion as to whether it will pass to the inner or the outer pole 

 (Figs. 1-3). In Fig. 3 it will probably pass inwards, as may be 



1 '13, '14, Arch. Zellforsch., Vol. XIII. 



399 



