No. 499] 



.! AV-.ir MEXDELIA.X RATIO 



437 



mottled offspring would be produced by every purple- 

 mottled parent, and there would be no equality between 

 the purple-mottled and black in many families of the 

 third and subsequent generations; but those F, ( families 

 which have been thus far investigated show a number 

 of instances in which purple mottled parents produce 

 no brown or brown mottled young and there is a con- 

 tinued equality between the mottled and self-colored 

 offspring of such parents. The remaining possi- 

 bility, namely, that individuals which carry the mottled 

 pattern, M, but are homozygous with respect to that char- 

 acter, are not mottled but self-colored, is the only one that 

 fits all of the observed facts. The mottled color-pattern 

 must be heterozygous in order to become apparent in the 

 hybrids. 



We may then indicate the composition of the group of 

 individuals of F 2 which carry the dominant mottling fac- 

 tor, M, and the expectation as to the composition of the 

 « > lis | iri ng which each will produce in F 3 as follows: 



1 PBMPBM = B1(B1) (M latent in all). 



2 PBMPBm = PM(1PM:1B1) (M latent in $ the Bl). 

 •2 PBMPbM =Bl(3Bl:lBr) (M latent in all). 



2 PBMpBM = B1(3B1:1W) (M latent in all). 



4 PBMPbm = PM(3PM:3Bl:lBrM:lBr) (M latent 

 in | the self-colored). 



4 PBMpBw — PM(3PM':3B1:2W) (.1/ latent in J the 

 Bl and £ the W). 



4 PBMpbM = Bl(9Bl:3Br:4W) (M latent in all). 



8 PBMpbm = PM (9PM : 9B1 : 3BrM : 3Br : 8W) (M la- 

 tent in \ the self-colored and f the 



It will be seen from this scheme that the mottled 

 pattern could exist and does exist as a latent (i, < 

 visible) character in pigmented beans just as well 

 the white bean, which is contrary to the assumption i 

 when I insisted that the mottled pattern must have 

 from the white bean. It is also obvious that the m< 



