824 THE AMERICAN NATURALIST. [VOL XXXII. 
ancestors by variation, and, after being tried by experience, 
are found favorable to the organism possessing them, and are, 
therefore, reproduced in their offspring. Cope and Henslow 
and others have called attention to this unmistakable meaning 
of natural selection. And Wallace, in 1866, criticised Dar- 
win’s use of the term “ Natural Selection ” by saying, “ Nature 
. . - does not so much select special varieties as exterminate 
the most unfavorable ones.” 
On the other hand, the recognition of the view that varia- 
tion is the prime factor of evolution, was evidently in the 
minds of both Lyell and Asa Gray, and was one of the chief 
causes of their hesitation, at first, to accept in full Darwin’s 
theory of evolution. But, as a theory to explain the origin of 
spectes, Darwin was right, for the fundamental characteristic 
of species is not variation, but the persistent reproduction of ` 
like characters,and natural selection and the direct and indirect 
effects of environment are the most potent agencies discovered 
in determining this persistent uniformity of reproduction. 
But producing uniformity is not evolution. 
The founders of the modern theory of evolution, while they 
were united as to the modification of species by descent, and 
in assuming that natural selection and kindred agencies were 
conspicuous factors in the general process of evolution, were 
not uniform in the assignment of the part played by these 
factors. Nevertheless, in the expressions of philosophical 
opinion regarding these points, above quoted, we find they 
were aware that the immediate effect of natural selection, 
etc., was in the direction of making characters hereditary, in 
“preserving ” them in the reproductive sequence of the race. 
With the preconception, and as I believe misconception, that 
heredity is the essential characteristic of living organisms, it 
was necessary to believe that the organism could not, of itself, 
evolve into something different ; hence the natural conclusion 
that variation must be zzduced by external agencies, and natu- 
ral selection, etc., are these agencies which stimulate and pro- 
mote variation, and at the same time check and hinder it. 
Herein lies one of the great inconsistencies of the orthodox 
theory. 
