of Heredity 21 



or in the modified form in which he restated it*, did not 

 express the phenomena of alternative inheritance known 

 to him with sufficient accuracy to justify its strict appli- 

 cation to them, and also on general grounds, proposed that 

 the phenomena of blended and alternative inheritance 

 should be treated apart a suggestion t the wisdom of 

 which can scarcely be questioned. 



Now the law thus imperfectly set forth and every 

 modification of it is incomplete in one respect. It deals 

 only with the characters of the resulting zygotes and 

 predicates nothing in regard to the gametes which go to 

 form them. A good prediction may be made as to any 

 given group of zygotes, but the various possible constitu- 

 tions of the gametes are not explicitly treated. 



Nevertheless a definite assumption is implicitly made 

 regarding the gametes. It is not in question that differences 

 between these gametes may occur in respect of the heritage 

 they bear ; yet it is assumed that these differences wall be 

 distributed among the gametes of any individual zygote in 

 such a way that each gamete remains capable, on fertilisa- 

 tion, of transmitting all the characters (both of the parent- 

 zygote and of its progenitors) to the zygote which it then 

 contributes to form (and to the posterity of that zygote) in 

 the intensity indicated by the law. Hence the gametes of 

 any individual are taken as collectively a fair sample of all 

 the racial characters in their appropriate intensities, and this 

 theory demands that there shall have been no qualitative 

 redistribution of characters among the gametes of any 

 zygote in such a way that some gametes shall be finally 

 excluded from partaking of and transmitting any specific 



* In Pearson's modification the parents contribute O3, the grand- 

 parents O'lo, the great-grandparents '075. 

 t See the works referred to above. 



