1899] THE SCOPE OF NATURAL SELECTION 197 
principle for selection to rely upon, since the male and female lines of 
heredity would be largely in harmony over the earlier stages of 
development, the tendency to vary being increased towards the later 
stages, thus the requisite stability and variability would be largely 
obtained. Finally, this theory involves no very great assumption ; it 
is, when examined, very little more than a series of inferences drawn 
from peculiarities of life that appear to be nearly or completely uni- 
versal in application, being dependent solely on the assumptions of 
mechanical and chemical limits to growth, the latter being no longer 
an assumption, but an established fact in some instances, on the 
innate capacity for growth, qualitative and quantitative specialisa- 
tion, and upon the conclusion that protoplasm is never directly in- 
fluenced by climatic conditions. The theory of co-incident variability 
and the non-inheritance of acquired responses would equally accord 
with this theory as with Weismann’s, while it would account for those 
cases of modifications which have been effected during the early stages 
of development. 
In conclusion, I have endeavoured to show reason for believing 
that the principle of selection, when rightly viewed, is the only theory 
which is capable of explaining the various phenomena in their entirety; 
that the properties existing in the lowest forms of life do afford 
sufficient material for natural selection to act upon, and therefore, until 
it can be shown that another theory is in more complete accordance 
with the facts, that natural selection must be regarded as the dominant 
factor of evolution. 
THE Grotro, 
HaMprTon-oN-THAMES. 
