The Presidential Address. 
89 
in bequeathing to us the true spirit of inquiry into Nature’s 
laws by legitimate method. The lustre shed by our Honorary 
Member upon the present age will not wax and wane with 
the fluctuations of opinion as to the efficiency of the “-sur¬ 
vival of the fittest,” but his influence will be felt throughout 
generations of posterity by virtue of that plasticity of mind 
which he conferred upon his contemporaries, compelling them 
to reconsider old doctrines, and ultimately effecting a com¬ 
plete revulsion in thought. In a Society such as this, com¬ 
prising as it does many young and aspiring naturalists, it is 
perhaps the more necessary to insist upon this moral con¬ 
veyed by Darwin’s teachings. It is true that there are some 
eminent men of science who, although evolutionists, do not 
admit the sufficiency of the Darwinian factors; but at the 
same time they could not deny that their acceptance of 
evolution in any form is entirely the result of Darwin’s 
influence. The discovery of the theory of selection was a 
very great contribution to science, but the establishment of 
the principle of evolution was a still greater contribution to 
philosophy. 
The question as to how far evolution can be legitimately 
admitted to have taken place in the organic world is by some 
considered to be open to discussion. It cannot be denied that 
the proof that natural selection is competent to modify 
species does not necessarily carry with it the proof that groups 
of great dissimilarity, such, for example, as the vertebrates 
and the molluscs, have sprung from a common stock. But 
those who admit evolution in principle need feel no distrust 
on this head, even if Palaeontology has not as yet supplied 
the transitional links. In cases of this kind, however, 
arguments of another order come in, and homology, embry¬ 
ology, &c., may be appealed to for completing the evidence 
that is wanting to bridge over the gaps in the chain of being. 
On this point Darwin is very explicit:—“ Throughout whole 
classes various structures are formed on the same pattern, 
and at a very early age the embryos closely resemble each 
other. Therefore I cannot doubt that the theory of descent 
with modification embraces all the members of the same 
