No. 533] INHERITANCE IN COLIAS PHILODICE 277 



dominant or recessive. If the latter be indicated, then 

 we may find that a suitable designation of the gametes 

 of Abraxas and Colias wonld be that suggested by 

 Wilson, 1909 b, viz., for the male YY and for the female 

 XY, Y being the small synaptic mate of X, which is the 

 large odd "female-producing" chromosome. 



On the other hand, if the male is dominant a state of 

 affairs that is exactly the reverse might be expected, viz., 

 an absence of a chromosome, or an abnormally small one, 

 in half of the eggs would be the visible sign of future 

 femaleness. If these conditions should be realized, we 

 might be able to identify the "equal idiochromosomes" 

 already found in the spermatogenesis of butterflies with 

 my XX of the male, the corresponding chromosome in 

 the male-producing type of egg being X, the female- 

 producing ova either lacking the chromosome altogether 

 or having one of reduced size. 



Dr. Castle, in a recent letter to me, expressed the 

 opinion that the well-known anabolic tendency of the 

 female, especially in reproductive activities, renders it 

 extremely probable, on the other hand, that the" female- 

 producing gamete in every case of disparity should have 

 the larger chromatic equipment. This seems to me very 

 plausible, and it may well be that the findings of cytology 

 in reference to this question can never do more than 

 demonstrate the presence of this constant anabolic tend- 

 ency in the female-producing gametes. The appearance 

 of the large X chromosome in the female-producing 

 gamete of the Hemiptera may be, therefore, only the 

 visible expression of a sex tendency already established, 

 as Morgan's observations on the cytology of Phylloxera 

 indicate. 



But the demonstration of this anabolic tendency, even 

 m the unfertilized gamete, does not mean necessarily the 

 presence of a sex determiner that is absent or deficient 

 m the male-producing gamete, and hence the dominance 

 of femaleness. It is just as reasonable to assume that the 

 constant katabolic tendency of the male, evinced possibly 

 by deficiency in chromatin at the start and certainly by 

 the presence of horns, high colors and elaborate plumage 



