206 



THE AMERICAN NATURALIST 



[Vol. LII 



sumption that coral was a member of the white allelomorphic 

 series. The heterozygous white-coral compound in the female is 

 intermediate in color between the two pure stocks. Coral is re- 

 cessive to red. A coral male crossed to a yellow-white female 

 gave all yellow-white sons and the intermediate (compound) 

 white-coral' daughters. Evidently the mutation took place in the 

 wild-type gene of the mother, since it is that gene which did not 

 occur in the daughter while the eosin gene of the father is re- 

 tained. It also occurred near the maturation divisions as only 

 one individual of the kind appeared. If the change had oc- 

 curred in the early stages of the egg, it would probably have re- 



Reappearance of White 

 In a cross of a bar male to a red-eyed female, which produced 

 251 offspring without a lethal sex ratio, one male was obtained 

 which was white, although there was no white in the pedigree of 

 either parent. This fly was found in one of the last counts of the 

 bottle and had the appearance of being a young fly. Counts 

 were made from the bottle every two days. Since I had no cul- 



white flies^n my etherizing bottle previously, the fly can not be 

 accounted for by assuming that it had remained in the etherizing 

 bottle from a previous count of another bottle. It is highly 

 probable, though not absolutely certain from these considera- 

 tions that this white male was not due to contamination, but 

 rather to a mutation in the wild type gene of a maternal chromo- 

 some. We may be sure that this change took place in the ma- 

 ternal chromosome rather than in that of the father, since males 

 always receive their one X-chromosome from the mother except 

 in relatively rare cases of non-disjunction, and in this case the 

 male would have been bar. 



In appearance the new white is not distinguishable from the 

 white of the original stock and is quite without color in both 

 males and females. Dr. A. H. Sturtevant has been testing the 

 effect of various concentrations of alcohol in extracting color 

 from the eyes of flies which are members of this multiple allelo- 

 morphic series and kindly added this new white to the material 

 which he tested. He reported that the new white is acted upon 

 exactly as is the original white. Genetic results showed the new 

 white to behave as an allelomorph of the old. The new white 

 male was crossed to a red sister and the offspring were all red. 



