GYXAXDROMORPHISM 165 



they may be supposed to produce male structures 

 (Fig. 83, B). 



The first case of the fly, in which one half the body 

 is male and the other female, would seem better in 

 accord with Boveri's hypothesis. In its support 

 also may be urged the fact that Boveri and Herbst 

 have shown that the belated sperm-nucleus may 

 unite with one of the two nuclei that result from the 

 first division of the egg nucleus. 



On the other hand, the second case of the fly (where 

 only a small part of the body is male) may be better 

 accounted for by my hypothesis. It is known that 

 single sperms that enter an egg without a nucleus, 

 or even with one, may divide. The two hypotheses 

 are not mutually exclusive, but rather supplementary. 



Toyama has described a gynandromorph in the 

 silkworm that arose in a cross between a race with a 

 banded caterpillar (the female parent) and a race 

 with a white caterpillar (the male parent). As shown 

 in Fig. 84, the gynandromorph was banded on the left 

 (maternal) side and white on the other (right) side. 

 When the adult moth emerged, the left side was female 

 and right side was male. Since the sperm alone bore 

 the white character, which is a recessive character, it 

 appears that the right side must have come from sperm 

 alone. This is in accordance with my hypothesis, but 

 I have also shown that Gynandromorphs may arise 

 through somatic dislocations of the sex chromosomes 

 in the early embryo. Gynandromorphs are not un- 

 common in insects, rare (or never present) in birds and 

 mammals. 



The explanation K f this difference is found, I think, in 



