43 
assumptions are essential to the theory; are they con 
sonant with the facts of nature ? 
(a) IS THE TENDENCY TO INCREASE IN A GEOMETRICAL RATIO 
FOLLOWED BY DISCRIMINATIVE DESTRUCTION ? 
“ Multitudes—multitudes in the Valley of Decision.”—(Joel. Hi., 14.) 
“ Thy crowned are as the locusts, and thy captains as the great 
grasshoppers, which camp in the hedges in the cold day, but when 
the sun ariseth they flee away, and their place is not known where 
they are.”—(Nahum. Hi., 17.) 
It is contended that the tendency to increase in a 
geometrical ratio necessarily produces a struggle for 
existence, and that the struggle for existence necessarily 
leads to the survival of the fittest. 
“A struggle for existence inevitably follows from the high rate 
at which all organic beings tend to increase.”—( Origin of Species. 
P■ 50.) 
“The power of selection brought into play through the struggle 
for existence and the consequent survival of the fittest.”—( The 
Variation. H., p. IQ2.) 
From the proved fact of the rapid increase of organisms, 
Mr. Wallace infers the struggle for existence as a neces 
sary consequence. Then taking the struggle for existence 
as a proved fact, he infers the survival of the fittest as 
a necessary consequence. And then, from the survival of 
the fittest as a proved fact, he infers the changes in 
organic forms ; and thus presents a demonstration of the 
transmutation of species by means of Natural Selection.* 
Mr. Romanes says :— 
“ If, on independent grounds, we believe in the theory of evolution 
at all, it becomes obvious that Natural Selection must have had 
* Contributions, p. 1 op.