THE GENETICS OF HABROBRACON JUGLANDIS ASHMEAD 



genetic composition. The male would be indi- 

 cated thus, r.+. He is type for mottled, there- 

 fore, the + sign may be omitted from his for- 

 mula leaving only the r to indicate that he is 

 both phenotypically and genotypically a mutant 

 with reduced wings. We may , therefore , indicate 

 this cross by the formula mo X r. The Fl het- 

 erozygous females produced from this mating 

 v;ould be phenotypically type but carry in their 

 genotype the recessive r and mo. Their formula 

 would then be +.mo/r.+ which maybe written mo/r 

 indicating that the mo gene was received from 

 their mother and the r gene from their father. 

 This again eliminates the + sign and simplifies 

 the formula. The Fl males produced would, of 

 course, all be mo. The Fl females, if set as 

 virgins, will produce four classes of sons in 

 gametic ratios, +, mo, r, mo.r. For clarity a 

 period is used to separate the symbols of the 

 double mutant. Since four classes of sons are 

 produced by the Fl virgin females we may be 

 certain that the mutants involved are not al- 

 lelic. On the other hand if only two classes 

 appeared as in some eye color crosses it would 

 indicate that the mutants involved were allelic, 

 each affecting the same character. 



In recording the F2 progeny t of the Fl fe- 

 males, it is advisable to assign each female 

 involved a number — 1, 2, 3, etc., and to letter 

 each successive vial through which they are 

 transferred — a, b, c, etc. Thus we have la, lb, 

 Ic, etc., for the first Fl female of the origi- 

 nal mo.X r cross. The progeny of each female 

 and for each vial through which she passes may 

 then be tabulated as in Fig. 10. The entire 

 Drogeny from each female in the experiment is 



70 



