418 TOWER, DARWINISM. 
DARWIN's Hypothesis of Natural Selection rests upon the fact 
that of the number of organisms produced in each generation, 
only a few survive to reach sexual maturity and become the pro- 
senitors of the next generation. This huge juvenile death-rate, while 
recognized by QUETELET and others before DARWIN, was used by 
DARWIN as the basis in fact, to which he added the hypothesis 
that those individuals attaining the adult condition were those best 
adapted to encounter successfully the conditions into which the 
accident of birth thrusts them. Nature was regarded as exercising 
a choice or a selective preservation of the best adapted members 
of each generation. In this action Nature was conceived of as 
operating in ways analogous to those employed by man in the impro- 
vement and alteration of races of domesticated plants and animals. 
If the Hypothesis of Natural Selection is accepted as true, either 
because it provides a facile means of explanation and interpretation, 
or is believed to be true for any other reason, there is comparatively 
little in the way of natural phenomena, especially among organisms, 
which cannot be explained and interpreted by Natural Selection. 
Difficulties, of course, are encountered, but not insuperable ones, 
since all that is necessary is to alter the field of selective activity 
from the individuals and their environment to portions of the 
individual, as in histonal selection, and when this does not suffice, 
with equal facility to move the theatre of combat for survival into 
the germ plasm. On this terrain, WEISMANN’S germinal selection 
is unassailable; can neither be observed nor investigated; and 
the principle of Natural Selection is rendered impregnable as the 
cause and explanation of the modification and evolution of organisms. 
The Hypothesis of Natural Selection, therefore, is most plausible 
and easily usable as well as one of the most elusive means that 
we have of interpreting and explaining problems relative to organisms. 
If the Hypothesis is accepted as true, because it can be used to 
explain so much without demanding more proof of its operation 
than is available, the user is explaining and interpreting nature 
on the basis of a belief. However, there are other beliefs derived 
from divers sources which are quite as facile in providing satis- 
factory explanations and interpretations. 

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