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And if a living dog is better than a dead lion, we may 
rest assured that, for purposes of organic evolution, a 
surviving race of dogs is better than an extinct race of 
lions. Moreover, the extinction of a species shows the 
incapacity of that species to adapt itself to certain con 
ditions. In the forests of Denmark, as we have already 
pointed out, the birch in vain struggles to survive in 
company with the beech. In such a case, it might have 
been expected that Natural Selection would have found 
out some modus vivendi for this threatened species. For 
by the theory, in adverse circumstances, variations of 
every kind arise, favourable variations are selected, and 
thus the organism is adapted to its conditions. But it 
has failed to do this. Extinction is not, in this case, the 
accompaniment of Natural Selection, properly so called. 
On the contrary, it testifies to the inefficiency of that 
supposed law of nature where its aid is most required. 
We have already shown that the extinction of one 
species by another species is not a proof of the transmu 
tation of species by means of Natural Selection ; because 
in all the cases cited, one species is exterminated and 
the other species remains unmodified. 
One of the reasons given by Mr. Wallace for the ex 
tinction of large animals is based upon the principles of 
Natural Selection. Large animals have few offspring, and 
therefore do not afford that opportunity for the output of 
great numbers which the accidental emergence of favour 
able variations requires. But it is quite clear that large 
animals have survived when the conditions have been 
favourable. If so, the slowest breeding animals will in 
crease their numbers immensely. Nor is it necessary for 
a race to bring forth a large number at one birth in order 
to survive the struggle for existence. “ The Fulmar petrel 
lays but one egg, yet it is believed to be the most numerous