THE EFFECTS OF CASTRATION 151 



are two types of females and one kind of male 

 (Fig. 66). 



Without giving the analysis of this case I may say 

 that the results can be explained on a Mendelian basis. 

 The peculiar feature of Gerould's explanation is that 

 two doses of the yellow-producing determiner in the 

 female give yellow color — one dose gives white. In 

 the male, on the other hand, one dose of yellow gives 

 yellow. 



The second case is that of Papilio memnon, worked out 

 by de Meijere from the experiments of Jacobson. There 

 is one male type and three female types, Fig. 76. De 

 Meijere accounts for the results of matings in this 

 species recorded by Jacobson on the assumption of 

 three factors, one for each type of female. The three 

 factors are treated as allelomorphs, and therefore only 

 two of them can be present in any one individual, and 

 since they are allelomorphs they will pass into different 

 gametes. The order of dominance is Achates, Agenor, 

 Laomedon. The male carries these same factors, but 

 they are not effective in him. Baur accounts for the 

 results in a somewhat different way, but involving or- 

 dinary Mendelian conceptions. 



An interesting case is that reported by Foot and 

 Strobell. They crossed a female of a bug, Euschistus 

 variolarius, the male of which has a black spot on the 

 end of the body (the female lacking the spot), with a 

 male of Euschistus servus that lacks the spot both in 

 the males and the females (Fig. 77). The daughters 

 had no spot ; the sons had a faint spot, less developed 

 than in variolarius. When these (Fi) offspring were 

 inbred, they obtained 249 females without a spot. 



