CHROMOSOME-GROUPS OF METAPODIUS AND BANASA. 313 



associated in the germ-cells. In the case of Mctapodius such a 

 tendency is shown in the more frequent coupling of the .y-chromo- 

 some with the small idiochromosome, which leads to its more 

 frequent passage to the male-producing pole, and hence to its 

 more frequent appearance in the male. This reminds us of cer- 

 tain crosses of Lepidoptera observed by Standfuss, 1 and more 

 recently by Doncaster and Raynor, 1 in which there is a tendency 

 for a particular set of specific or varietal characters to appear 

 more frequently in one sex than the other. Thus, in Abraxas, 

 as reported by the last named observers, after crossing the 

 original form (A. grossulariata} with an albinistic variety (lacti- 

 color] to which it is dominant, the cross rf* DR x 9 RR gives 

 both sexes of both forms, but the reverse cross 9 DR x cT RR 

 results in a sharp separation of the sexes of the two forms, all 

 the resulting males being DR and the females RR. This, as the 

 authors show, may be explained by the assumptions, first, that 

 the sex borne by the egg is uniformly dominant (as appears to 

 be the case in the Hemiptera) and second that the dominant 

 somatic character (Y. e. t the grossulariata pigmentation) uniformly 

 couples with the male character in the egg while in the sperma- 

 tozoon no coupling occurs. Such a chromosome-coupling as 

 that observed in Metapodius terminalis gives a very definite basis 

 for the possible explanation of couplings of the sexual characters 

 with specific or varietal ones ; and it seems possible that we may 

 in this direction find a means of testing decisively the whole 

 chromosome-theory of heredity. In the case of Metapodius I 

 have not thus far been able to find any constant differences 

 between individuals of Types A and B ; but only the external 

 characters are available for examination. I hope hereafter to 

 examine this question more thoroughly, both in Metapodius and 

 in Banasa. 



ZOOLOGICAL LABORATORY, COLUMBIA UNIVERSITY, 

 February 4, 1907. 



1 See Castle, Bull. RIus. Comp. Zoo/., XL., 4, 1903. 

 2 Proc. Zool. Soc. London, June 7, 1906. 



