1898] SCIENTIFIC PROOF v. ‘A PRIORI’ ASSUMPTION 105 
On the other hand, where vrass is allowed to grow to 2 or 3 
feet high, all such dwarf plants rapidly disappear. The former con- 
querors over mown grass cease to be victorious and disappear where 
their own victims previously had a hard time of it. 
Similarly in a neglected kitchen garden a row of peas, unstaked, 
have succumbed to chicken-weed, Urtica wrens, Solanum nigrum, 
oroundsel, &e.; but a row supplied with sticks have grown up in 
defiance of their enemies. 
Thus natural selection soon decides what shall be smothered and 
which shall proclaim itself the fittest to survive. It thus brings 
about the distribution of plants, but no one has ever shown that 
its sphere of action in any way concerns the origination of specific 
characters. 
The three principal & priori assumptions upon which Darwin’s 
theory was based, then, are as follows :-— 
(1) The first assumption was that individual variations are the 
source of varietal variations (“ Origin of Species,” 6th Ed., p. 54). 
(2) The assumption that plants vary indefinitely under changed 
conditions of life. 
(3) The assumption that natural selection eliminates the unfit 
and retains the fittest to survive among indefinite variations, 7.e., of 
numerous offspring of any one and the same species. 
Darwin based his theory mainly upon these assumptions, and 
more than one of his followers seem to rest satisfied when they say 
that there is no evidence in the present state of our knowledge, and 
think that is an all-sufficient answer to the demand for scientific 
proof. This self-satisfied attitude of professing ignorance of any 
facts, wherewith to support the theory, seems to me to be the 
most remarkable, and I would add, deplorable position possible, 
for any one professing to be a scientific man, to take. I can 
only regard it as an alarming evidence of the evil growth of a 
belief in & priori assumptions, as if they were scientific methods 
of proof. 
What is the cause of this eager pursuit of subjective will-o’-the- 
wisps, instead of the study of objective facts? Is it that it is so 
much easier to sit still and imagine how things may go on in nature 
than patiently to investigate and accumulate storehouses of facts as 
Darwin did? Unfortunately he attributed to natural selection a 
role to play which it could not undertake. The result was inevi- 
table. The facts of variation under changed conditions of life are so 
obvious that his books teem with instances, and then natural selec- 
tion drops out of sight. When, however, he is arguing on behalf of 
natural selection, then definite variations seem to be allowed to drop 
into the background. Hence his “ Origin of Species” and “ Animals 
and Plants under Domestication ” are full of these two opposite drifts. 
H 
