156 Evolution and Adaptation 
standard of successive generations could ever be raised be- 
yond the most extreme fluctuating variation. At least this 
appears to be the case if individual, fluctuating variations be 
the sort selected, and it is to this kind of variation to which 
Weismann presumably refers. Without discussing this point 
here, let us examine further what Weismann has to say. He 
thinks that while in each form there may be a very large 
number of possible variations, yet there are also impossible 
variations as well, which do not appear. ‘The cogency, the 
irresistible cogency as I take it, of the principle of selection 
is precisely its capacity of explaining why fit structures al- 
ways arise, and this certainly is the great problem of life.” 
Weismann points out that it is a remarkable fact that to-day, 
after science has been in possession of this principle for 
something over thirty years, “during which time she has bus- 
ily occupied herself with its scope, the estimation in which 
the theory is held should be on the decline.” ‘It would be 
easy to enumerate a long list of living writers who assign to 
it a subordinate part only in evolution, or none at all.” 
“Even Huxley implicitly, yet distinctly, intimated a doubt 
regarding the principle of selection when he said: ‘ Even if 
the Darwinian hypothesis were swept away, evolution would 
still stand where it is.. Therefore he, too, regarded it as 
not impossible that this hypothesis should disappear from 
among the great explanatory principles by which we seek 
to approach nearer to the secrets of nature.” 
Weismann is not, however, of this opinion, and believes 
that the present depression is only transient, because it is only 
a reaction against a theory that had been exalted to the 
highest pinnacle. He thinks that the principle of selection 
is not overestimated, but that naturalists imagined too quickly 
that they understood its workings. ‘On the contrary, the 
deeper they penetrated into its workings the clearer it ap- 
peared that something was lacking, that the action of the 
principle, though upon the whole clear and representable, yet 
