4r>o 



THE AMERICAN NATURALIST [Vol. XLIX 



eyes were red, sex combs lacking, left wing long, and the ab- 

 domen characteristically male. The external genitalia were 

 apparently half male and half female. This is not a fore and 

 aft gynandromorph bul a lateral one in which the parts involved 

 are restricted to the abdomen and the posterior part of the 



The fly was courted assiduously by males but it would not 

 mate. The gonads on both sides were female and ripe eggs were 

 present. It is probably true that the rggs could not be deposited 

 on account of some defect in the oviducts. 



IV. The origin of this fly was the same as the last two, i. e., it 

 came from a cross of cherry club vermilion with the wild type. 

 The eyes were red. sex combs lacking; the wings were of the same 

 length; the abdomen was divided into a female and a male side 

 and the external genitalia were apparently half female and half 

 male. Anteriorly the fly was female, and posteriorly it was half 

 male and half female. 



A male courted this gynandromorph as long as the male re- 

 mained in front of it. When the male with one wing > ilual in- 

 made a half circle to the tip of the abdomen, it immediately 

 dropped its wing and turned and ran. Sections showed mature 

 spermatozoa in both testes. 



V. This gynandromorph arose from the cross of 



from so few data, is that the gonads of lateral gynandromorphs 

 do not follow the separation of the somatic cells into a male and 



or female. Since the cells of an early embryo must be either 

 male or female producing, we can understand why the gonads 

 of a gynandromorph should be alike on both sides, regardless of 

 the somatic condition, if we suppose that the gonads are derived 

 from a single cell of the embryo. 



F. N. Duncan 



