SEX-CHROMOSOMES OF PSYCHID/E. 



403 



point of fact, I have two perfect pairs of daughter-plates, each 

 with 29 chromosomes (see Table I., nos. 33, 34). No X-chro- 

 mosome is present in these cases. If we leave these out of account 

 there remain 35 females and 25 males, a sex-ratio of 1.36: I in 

 favor of the female, that is to say, exactly the ratio to be expected 

 from observations on the maturation-phenomena in the Tornow 

 race. Possibly the embryos with 58 chromosomes may have 

 arisen by the development of unfertilized eggs. 



2. Fitmea casta PALL. 



The equatorial plate of the first maturation-division in the 

 egg shows 31 chromosomes. One of these must be univalent, 

 for the daughter-plates show in some cases 31 chromosomes, in 

 others 30. As in Tal<zporia, an X-chromosome is present but 

 strange to say it fails to lag behind the autosomes and passes 

 together with them to one spindle-pole. Fig. 23, from a perfect 

 plate with 30 chromosomes, clearly shows the natural size-rela- 

 tions. Figs. 19 and 20, 21 and 22, 24 and 25 are three pairs of 

 daughter-plates, from the interkinesis, in which the chromosomes 

 are perfectly clear and well-separated; but unfortunately the 

 plates lay obliquely, so that the photographs seem to show certain 

 fusions which do not really exist. Text-figure I shows the same 



TEXT FIG. i. 



