12 
A. I). Darbishire. 
are composed of contributions from its several ancestors, the 
magnitude of the contribution varying directly with proximity of the 
contributing ancestor. 1 It is first necessary to prove that this has 
been the general view of the question. This will not he a 
matter of much difficulty. For it seems to me to he manifest that 
it was some such view as this which has led the breeder to confine 
his attention to the somata of the material with which he deals, and 
to believe that by breeding from individuals with a particular 
character for a sufficient number of generations, it is possible to 
“ breed out ” other, undesirable, characters. Further, there must 
have been some preconceived idea of heredity against which, as a 
sort of background, the facts of Mendelian inheritance appear 
striking and unexpected. And this preconceived idea was in my 
opinion the theory of Ancestral Contributions. For the fact that, 
for instance, the green individuals which reappear in F 2 from a 
cross between a yellow and a green Pea, produce nothing but 
greens (when mated together) in spite of the fact that both of their 
parents were yellow and that half of the sum total of their previous 
ancestors were also yellow, is only surprising to anyone who holds 
that the characters of an organism are determined by the somata 
of its parents and more remote ancestors. 
As I have already said, the substitution of the Weismannian 
view for the contributional view of heredity is not yet complete. 
The process has, however, been much more rapid during the last 
eight years owing to the support which Weismann’s doctrine has 
received from the facts discovered by Mendel and by those who have 
followed him. Still, even those facts have not sufficed to destroy a 
1 It is possible that the objection may be raised at this point that 
the principle which I have just formulated is none other than 
Gabon’s Law of heredity. This is not the case. I have 
shown elsewhere (On the Difference betiveen Physiological and 
Statistical Laws of Heredity, Mem. and Proc., Manchester Lit. 
and Philosophical Society, Vol. 5, Pt. 3) that the controversy 
which followed the resuscitation of interest in the phenomena 
of Heredity by the rediscovery of Mendel’s papers would not 
have taken place if a clear distinction had been drawn between 
statistical and physiological laws of heredity. Gabon’s 
law was a first attempt to reduce the chaos of hereditary 
phenomena to order ; and this antithesis was naturally not 
before his mind. But if Gabon’s generalization be understood 
as a physiological theory applicable to individual cases, an 
interpretation which 1 do not think his own formulation of 
it warrants, the theory of ancestral contributions only differs 
from Gabon’s Law in that the exact amount of the contri¬ 
bution of each ancestor is specified in the latter ; if, however, 
Gabon's Law be understood as a statistical statement as to 
the composition of successive generation which is not true of 
the individuals which compose them, it has nothing to do 
with the theory of Ancestral Contributions. 
