president’s address. 
4S7 
•Chambers and proved by Darwin ; the theories advanced gained adher- 
•ents, and, as fact after fact was brought to light, which sustained the 
idea, men gradually became reconciled to it. * It may be of interest to 
observe that the theory of the survival of the fittest in the process of 
evolution was reached by two thinkers acting independently of each 
other. This theory is held to account for the variation and develop- 
ment which have taken place, and which are taking place in the 
origination and creation of species. Mr. Chambers declared ihat there 
was a principle of progressive development. He did not, as I have 
already stated, explain how or why there was such a law. Mr. Alfred 
R. Wallace and Charles Darwin thought out the subject. Mr. 
Wallace’s statement of his share in the matter is an interesting para- 
graph in one of his latest books, page 140 : 
“ While considering, he says, the problem of the origin of species, 
something led me to think of Malthus’ Essay on population which I had 
read about ten years before, and the positive checks — war, famine, 
disease, accidents, etc., — which he adduced as keeping all savage 
populations nearly stationary. It then occurred to me that these 
checks must also act upon animals, and keep down their numbers ; 
and as they increase so much faster than man does, while their 
numbers are always very nearly if not quite stationary, it was clear 
that these checks in their case must be far more powerful, since 
a number equal to the whole increase must be cut of! by them 
every year. While vaguely thinking how this would affect any species 
there suddenly flashed upon me the idea of the survival of the 
fittest — that the individuals removed by these checks must be on 
the whole inferior to those that survived. Then considering the vari- 
ations continually occurring in every fresh generation of animals or 
plants, and the changes of climate, of food, of enemies alwa}^s in pro- 
gress, the whole method of specific modification became clear to me, 
and in the two hours of my fit I had thought out the main points of 
the theory. That same evening I sketched out the draft of a paper ; 
in the two succeeding evenings I wrote it out and sent it by the next 
post to Mr. Darwin. I fully expected it would be as new to him as it 
was to myself, because he had informed me by letter that he was 
engaged on a work intended to show in what way species and varieties 
differ from each other, adding, my work will not fix or settle anything, 
I was therefore surprised to find that he had really arrived at the very 
