O^HEOUGH CUMULATIVE SEGREGATION. 



267 



fertility, especially in tlie case of flowers that failed of securing 

 a cross. And afterwards, when it came into competition with the 

 equally adapted variety from which it was partially protected by 

 Segregate Vigour, it would neither be driven out nor lose its 

 separate existence in a commingled race. It will be observed 

 that we have in such a case Local, Germinal, and Floral Segre- 

 gation, each producing partial effects which are enhanced by the 

 Segregate Vigour. In order to bring out the relation of these 

 factors to each other, let us assume definite values for each. 

 Let us suppose that ^ of the flowers are self-fertilized, are 

 fertilized with pollen from another flower of the same plant, 

 are fertilized with pollen from other plants of the same new 

 variety, and are fertilized with pollen from the older variety 

 occupying contiguous areas. Therefore the sum of the segre- 

 gating influences, which is called the " Ratio of pure breeding," 

 and is represented by E in Table IT., equals ; and the " Ratio 

 of cross-breeding," represented by c in all the tables, equals 

 Again, let us suppose that the fertility of the pure breeds is the 

 same as that of the half-breeds, but that the superior vigour of 

 the former is such that any one of the pure seeds has twice as 

 good a chance of germinating, growing to maturity, and producing 

 seed as any one of the crossed seeds. The general eflfect on the 

 final result will in that case be the same as if the " Ratio of 

 increase for the pure unions " (which I call M) equalled 10, 

 while the " Ratio of increase for the cross unions " (which I call 

 vn) equalled 5. Turning now to Table V., we can easily find the 

 ratio in which the number of pure-breeds will stand to the half- 

 breeds, if the conditions continue long; for in the column in 

 which m equals 5 and in the line marked c=y^J we find -f-^^ 

 which means that the half-breeds will equal the pure-breeds 

 multiplied by or by yg-. 



Segregate Vigour and Segregate 'Fecundity between Human Races, 



My attention has recently been called to the following facts 

 relating to the Japanese and Aino races, who have for many 

 centuries met under circumstances favourable for interfusion 

 without any apparent effect of this kind. I quote from ' Me- 

 nioir.s of the Literature College, Imperial University of Japan,' 

 No. 1 : " The Language, Mythology, and G-eographical Nomen- 

 clature of Japan viewed in the Light of Aino Studies," by 

 Basil Hall Chamberlain, p. 43 : — 



