THE ORIGIN OF GYNANDROMORPHS. 85 



we must search for some other kind of explanation for Toyama's 

 gynandromorphs. Fortunately, Doncaster's observation on the eggs 

 of a race of Abraxas gives us a clue to an explanation. Doncaster, 

 as stated on page 20, found occasionally an egg containing two nuclei, 

 each nucleus being about to be fertilized by a separate spermatozoon. 

 Now, if in Toyama's case the zebra mother was heterozygous, one of 

 the two nuclei in question might contain a Z chromosome and an auto- 

 some with a gene for plain color (Z and white), while the other nucleus 

 might contain a W chromosome and an autosomal gene for zebra (W 

 and zebra). Two sperms of the father, each with a white-bearing 

 autosome, each fertilizing one egg nucleus, would give a white male 

 side (Z, white; Z, white) and a female zebra side (W, white; Z, zebra). 

 This seems the most probable interpretation. 



There is still another possible explanation of Toyama's gynandro- 

 morphs, viz, that the male parts have come from the fusion of nuclei 

 derived from two (or more) spermatozoa. Pairs of such nuclei would 

 give ZZ cells that would be male and paternal. It is true that Herlandt 

 and Brachet find in the frog that sperm nuclei do not fuse in the egg, 

 but they attribute this to the cy tasters that keep them apart. If 

 in the moth (and bee?) the cystasters are less well developed, con- 

 tiguous nuclei might sometimes fuse. 



Another moth, Abraxas, has been extensively used by Raynor and 

 Doncaster in genetic experiments. The characters in question (gros- 

 sulariataveTSus lacticolor) show sex-linked inheritance and should furnish 

 interesting evidence as to the nature of gynandromorphs in moths. 



Quite recently Doncaster has reported two gynandromorphs of 

 Abraxas that arose in a cross between these two types. The first 

 case arose in a cross between grossulariata female by lacticolor male. 

 The normal expectation for this cross is: grossulariata males and 

 lacticolor females. There were produced 24 lacticolor females, no 

 grossulariata males, and one gynandromorph that was lacticolor but 

 mixed in certain parts. The absence of males is apparently con- 

 nected with an exceptional chromosomal condition in this family 

 (viz, 55 chromosomal line) of such a sort that all the fertilized eggs 

 lacked a chromosome, the single Z passing out into the polar bodies 

 in all or nearly all cases. The main characters of this gynandromorph 

 are "the right antenna is male, the left female, and the frenulum of 

 the left wing is of the male type and well developed, that of the right 

 male but imperfect. In the external genitalia the chief points are 

 that the uncus, anus, and ovipositor are each divided; the right vulva 

 is not unlike that of a normal male, the left side is abnormal and has 

 attached to it a second anus and half of the ovipositor," etc. Don- 

 caster sums up the chief peculiarities of this moth as follows: 



" (1) That though predominantly male, it has the lacticolor character which, 

 from its parentage, should be confined to females; (2) throughout the body 



