524 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1926 
“ The root of the difficulty that troubled Bateson is found, I think, 
in the title of Darwin’s book of 1889, ‘The Origin of Species by 
Means of Natural Selection.’ Bateson’s chief contention, if I un- 
derstand him, is that the theory of natural selection does not ex- 
plain the distinctive features of species, namely in that their dis- 
tinctiveness often rests on trivial characters that are not variable 
but constant. How, he asks repeatedly, could species be created 
by natural selection if those parts that distinguish related species 
from each other are concerned with parts not essential to the life 
of the individual? This undoubtedly raises a serious question for 
Darwin’s theory, but I venture to think that it is not so serious as it 
appears unless one accepts Bateson’s interpretation of the nature and 
existence of ‘species.’ In the first place, it is to be remembered 
that although Darwin entitled his work the ‘Origin of Species,’ 
his whole argument went to show that the attempt to sharply sep- 
arate species from varieties was futile because in most cases there is 
no such sharp separation. If this is conceded, then natural selection 
may offer an approximate solution of the situation as it exists. But 
Bateson believes that there are distinctions, essential ones, that give 
species a particular hierarchy in the realm of organic life. If so 
much be granted, the difficulty he points to may seem to be real. 
But there is another interpretation not fully appreciated at the time 
when Bateson wrote (although more than hinted at in Darwin’s writ- 
ing) which has been established by modern work in genetics. ‘This 
consideration goes far towards meeting the difficulty raised by Bate- 
son, even conceding, for the sake of the argument, his point that 
some species at least are sharply separated by constant characters 
that seem unimportant for their existence. I refer to the discovery 
that the effects of the gene are as a rule widespread, affecting many 
parts of the body at the same time. If, now, some of these effects 
involve the physiologicial actions essential to the individual’s exist- 
ence, other effects of the same gene may be structural but no less 
constant even though trivial. Natural selection, having ‘fixed’ the 
former, will incidentally include the latter. The argument is no 
longer an appeal to ignorance but to established fact. Its implica- 
tions only are theoretical. 
“There is another problem intimately bound up in Bateson’s 
arguments with respect to the species question. ‘he origin of infer- 
tility between species and the sterility of the hybrids produced by 
‘species crosses.’ Both questions were much discussed by Darwin 
with a fullness of information and open mindedness never since 
surpassed. Personally, I believe that he practically met the re- 
quirements of the situation. More recent work substantiates, I 
think, the essentials of his argument. In fact, the difficulty raised 
by Bateson deals the mutation theory of evolution a harder blow 
