Manchester Memoirs, Vol. I. (1906), No. II. 9 



one. And the reason again of this is that Galton's Law is 

 confused with another one which resembles it in one 

 respect, but differs from it in being would-be explanatory. 

 The remarkable thing about this Law is that whilst it is 

 characteristic of most Laws to be enunciated and receive 

 a name first and then become widely believed in after- 

 wards, the reverse is the case with this one ; for it is 

 believed in by all biologists who are not Mendelians, by 

 all breeders of animals or plants, and by all persons not 

 belonging to these classes who think about heredity at all. 



But it has not yet received a name. I propose to call 

 it the Laiu of Diminishing' Individual Contribution. 



According to it : the germ plasm of an individual con- 

 tains contributions from all of its progenitors : the amount 

 of the contribution being large in proportion as the progenitor 

 is near, i.e., large in the case of the parents, smaller in the 

 case of the grandparents, and so forth. 



It is a very good type of biological Law : it has the 

 advantage of simplicity : it is also, except in a few cases, 

 untrue. 



I will now give 3 cases to shew how widespread belief 

 in this Law is. 



The first that I give is that of the result of crossing a 

 yellow and white pink-eyed Japanese waltzing mouse with 

 a pink-eyed white mouse — that is, an albino. The result 

 is, usually, a black-eyed grey mouse.* And to anyone not 

 familiar with it, the result is most astounding : it is quite 

 the opposite of what one would expect. Expect from 

 what ? From one's — possibly unconscious — belief in the 

 Law of Diminishing Individual Contribution. 



Another case. Now that we know that a blue Anda- 

 lusian fowl is a heterozygous form produced by mating a 

 black and a white ; and that Andalusians when mated 



* Darbishire, :04a, p. 7. 



