Oiounence of difterent systems of gametic reduplication. 27 



Summary and Couclusioiiis. 



When a uoriiial- marked white cocoon -spinner was mated to the 

 plain-coated yellow strain, the FiS are all normal yellows, g:iving 

 F2 offspring' in the ratio 2 normal yellows : 1 normal whites : 1 plain 

 yellows. 



The phenomenon ajiiteared. at first sight, tempting to the supposit- 

 ion that an ordinary comi>lete repulsion occurs between N and Y. 

 Further investigations revealed, however, that this was not the case, 

 but the gametic distribution was definitely diffeient in the male and 

 female of heterozygotes. The gametic series in spermatogenesis was 

 1 NY : 3 Ny : 3 nY : 1 ny or 1 NY: 2 Ny -.2 nY: 1 ny, that is a partial 

 repulsion exists here, while that in ovogenesis was 1 Ny : 1 }>Y, that 

 is a complete repulsion is caused there. 



B\ moricaud yellows derived from the cross between moricaud 

 yellow and normal or plain white will produce four Fä forms, moricaud 

 yellow, moricaud white, normal or plain yellow, and normal or plain 

 white in a ratio fairly close to 177 : 15 : 15 : 49, which would have 

 been expected from the union of the gametic series (7:1:1:7) 9 X 

 (7 : 1 : 1 : 7) cf. However, th(! coupling system in this case was not 

 actually 7:1:1:7, the heterozygous male giving, when crossed with 

 double recessive female, the offspring in the proportion 3 : 1 : 1 : 3 or 

 2:1:1:2. The results of the reciprocal cross, diheterozygous 9 X 

 double recessive cT, were not yet obtained. But there is every reason 

 in supposing that a complete coupling between M and I' is caused in 

 ovogenesis of Fi moricaud yellows (MYmy). If this is the case, and 

 the male gametic distribution is assumed as 3:1:1:3, Fs zygotic 

 series will be 11 MY: 1 My : 1 mY : 3 my. This proportion fits the 

 actual results very well. 



Thus we may re])reseut the gametic series of the heterozygotes 

 in marking- colour reduplication in general terms as follows. Express 

 the allelomorphic pairs as 



^■1 = epistatic marking character, 

 a =; hypostatic 

 B = yellow cocoon colour and 

 b = white ., ,, , 



then the gametic series will be as follows: — 



