296 



Reduplication in Gametic Series 



the gametes Ah and aB, the gametes produced by the heterozygote so 

 derived form one or other term of the series 



AB: ^Ab 

 AB'. 7Ab 

 AB : 15Ab 



SaB : ab, 

 7aB : ab, 

 15aB : ab, &c. 



And if we take 2n as the number of gametes in the series we may 

 generalise it under the expression AB : (n—l) Ab : {n — l)aB : ab. 

 As the repulsion increases in intensity it is obvious that the zygotes 

 of the form A ABB and aabb will become relatively scarcer, for there 

 will be only one of each of these two homozygous forms in the complete 

 series of zygotes. At the same time the ratio of the three zygotic 

 forms AB : Ab : aB approaches more and more nearly to the ratio 

 2:1:1 such as would occur if the repulsion were complete. This is 

 brought out in the upper part of Table II where we have set out some 

 of the gametic series in which partial repulsion is involved together 

 with the series of resulting zygotes. The latter, as the Table shews, 

 are covered by the general formula 



(2n^+l)AB : {ri'-l)Ab : {n^--i)aB : ab*. 



Partial repulsion ' 



from zygote 



of form 



AbxaB 



Partial coupling 

 from zygote . 

 of form 

 ABxab 



Hitherto the only repulsion series which we have been able to identify 

 with certainty is the one with which we have just dealt, i.e. 1:3:3:1 

 series for the factors N and F. 



* The general formulae made use of here and in Table II are purely empirical, and 

 offer a convenient way of calculating the nature of the zygotic series from any series 

 of gametes. 



