J. M. WOODT.OCK 187 



unisexual lacticolor stock : there is nothiiii; in the hypothesis given 

 above that would account for it. 



One further speculation may be of interest — the form " Q " is in 

 some respects so like lacticolor that one is inclined to wonder whcither 

 it may have been produced by the loss of a similar constituent from the 

 normal gvossulariata. But since the factor which turns lacticolor into 

 grossidariata is sex-limited in transmission by the female while that 

 which turns " Q" into r/rossKlariata is not, on the hypothesis that 

 Mendi'lian factors are borne by chromosomes, it must be supposed that 

 the factor G is in the sex-chromosome while the factor T is in some 

 other chromosome. It might be possible, therefore, for lacticolor to 

 have arisen from grossidariata by the loss of some constituent of the 

 sex-chromosome, while "Q" arose by the loss of a similar con.stituiiit 

 from a different chi'omosome. 



EXPLANATION OF PLATE XXX. 



Figs. 1 — 3. Lacticolor J , ? , and underside. 



Figs. 4 — 6. "Q" i, s, and underside. 



Figs. 7, 8. i and ? of form with gap in the row of spots outside the yellow band ; 



this form is possibly heterozygous for "(J." 

 FigB. 9, 10. Normal (/rossulariata, <f and ? . 



