Prof, Agassiz on the Origin of Species. 149 
selves change in consequence of their own acts, by changing their mode 
of life, etc, this is the view of Lamarck ; others still assume that ani- 
mals and plants tend necessarily to improve, in consequence of the 
“truggle for life, in which the favored races are supposed to survive ; 
is 1s the view lately propounded by Darwin. elieve these theories 
will, in the end, all share the fate of the theory of spontaneous genera- 
ions so called, as the facts of nature shall be confronted more closely 
, T 5 : 
with the theoretical assumptions. The theories of DeMaillet, Oken, 
and Lama 
tion of Darwin, which has crept into the title of his work, is, that fa- 
e preserved, while all his facts go only to substantiate the 
ttion, that favored individuals have a better chance in the struggle 
or life than others, 
individuals 
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ong-continued investigations and for which the existing theories af- 
ation. It can certainly not be said that Darwin’s the- 
‘at ny Twin’s preservation of favored races. e difficulty would 
Y be to prove that they agree with the facts of Nature. It might be 
for instance, that any one primary being contained the possi- 
all those that have followed, in the same manner as the e ¢ 
ing about the nature of the operation by which the 
ced. Since the knowledge we now have, that similar 
