No. 533] INHERITANCE IN COLIAS PHILODICE 279 



male are dominant characters eventually produced in 

 the adult, according to my view, by the presence in the 

 oosperm of a double quantity of a male-producing 

 enzyme or similar substance. This hypothesis does not 

 depend upon cytology for its support, though it is not 

 impossible that future discoveries in oogenesis may be 

 found to be in harmony with it. 



6. DlMORPHS 



If complete separation of the yellow- and the white- 

 bearing gametes should fail to occur in the oogenesis of 

 the white female of Colias, in the differential division of 

 an oocyte destined after fertilization to become a female 

 individual, then the right wings of the future butterfly 

 might be white, the left yellow, or vice versa. Such an 

 individual, captured by Mr. J. H. Rogers, Jr., of Mod- 

 ford, Mass., is figured in Psyche, Vol. X, PI. X, Pig. 4. 

 A similar specimen of Colias cdusa, the right wings 

 being white, is figured by Fitch, 1878, in the Entomol- 

 ogist (No. 178, pp. 49-61). Fitch shows also a female 

 with the fore wings white and the hind wings yellow. 

 \ gynandromorph might be produced by similar failure 

 in the separation of a gamete containing' the sex de- 

 terminer from one lacking it. Various combinations of 

 color and sex are theoretically possible in one individ- 

 ual, if we assume that imperfect division of the gametes 

 may occur in gametogenesis. The discovery of these 

 combinations in nature, or their production by artificial 

 disturbance of the ova, is well within the limits of possi- 

 bility. 



The production of a dimorph with one side yellow and 

 one white is easily explained if we assume, for example, 

 that the determiners for yellowness and for whiteness, 

 after synapsis, reside in a single bivalent chromosome, 

 which fails to divide differentially in oogenesis, but 

 passes over bodily into one of the gametes, the egg. If 



