H. Onslow 



•2:n 



The bnikon line indicating tho oxochs yi-Ilow in Kij^. .'{ H netj. niiiH iih 

 usual cItHk'ly |M»nillfl to the onm^t' rurvr. I'xcfpt for a Hhiirp |MMik in 

 the pale n»jjion. whi<'h is no doiiht tuily an irnt,nilarity raiiM<'(l hy an 

 insutticiency t>f nunih»'i-s. 



(r> /////>/•/(/' {lutea x (fntss.) x var. Intra. 



A grinip of small families, none of t hem lar^e enough to he treated 

 8ejwn»tely. has Wen Hi-st dealt with (Fig. 4). Am would be ex|x'ct«Ml 

 in this tyjK' of mating (Dli x HH) the ofVspiing segregate into tw(j 

 8epj»rat<» classes. Tlu' hybrid insects have a value of ()H-2"4, and the 

 yellow insects one of 24 or above. The curve reaches a minimum at 2*2, 

 and the two maxima occur at just about the mean orange value of the 

 yellow and hybrid parents respectively. The areius of the two curves 

 should be tH]ual, and should repn*sent the number of individuals in each 

 class; actual measurement shows that the percentage «»f the dominant 

 form is 54, and that of the recessive form 40. The yellow values show 

 a rather definite decline for the luted homozygotes. 



>.8 

 o 



c 

 o 



3 



V 6 



5 Colour-units 



[1-3 :M] 

 Mean colour- 

 value of 

 hybrid parents 



[31: 2-6] 

 Mean colour- 

 value of 

 lutea parents 



Fig. 4. (Cf. Fig. 17.) Curve showing frequency distribution of the 

 orange and yellow colour-values of the oflfspring from 10 pairings of 

 hybrid {lutea x gross.) x lutea. 



* Although the word "hybrid" strictly applies to species-crosses, it has been retained 

 instead of the preferable term "cross-bred," since it was too late to make alterations in the 

 figures at the end of the paper, where the first term had unfortunately been printed. 



