ii] PROCESSES IN HEREDITY. 13 



by what we may see in plots of wild vegetation, where 

 two varieties of a plant mix freely, and the general 

 aspect of the vegetation becomes a blend of the two, 

 or where individuals of one variety congregate and take 

 exclusive possession of one place, and those of another 

 variety congregate in another. 



A peculiar interest attaches itself to mutually exclu- 

 sive heritages, owing to the aid they must afford to the 

 establishment of incipient races. A solitary peculiarity 

 that blended freely with the characteristics of the parent 

 stock, would disappear in hereditary transmission, as 

 quickly as the white tint imported by a solitary Euro- 

 pean would disappear in a black population. If the 

 European mated at all, his spouse must be black, and 

 therefore in the very first generation the offspring 

 would be mulattoes, and half of his whiteness would 

 be lost to them. If these mulattoes did not inter- 

 breed, the whiteness would be reduced in the second 

 generation to one quarter ; in a very few more genera- 

 tions all recognizable trace of it would have gone. 

 But if the whiteness refused to blend with the black- 

 ness, some of the offspring of the white man would be 

 wholly white and the rest wholly black. The same 

 event would occur in the grandchildren, mostly but 

 not exclusively in the children of the white offspring, 

 and so on in subsequent generations. Therefore, 

 unless the white stock became wholly extinct, some 

 undiluted specimens of it would make their appear- 

 ance during an indefinite time, giving it repeated 



