INDEFINITELY FROM THE ORIGINAL TYPE: 33 
the weakest—the very young, the aged, and the 
diseased —while those that prolong their existence 
can only be the most perfect in health and vigour— 
those who are best able to obtain’ food regularly, and 
avoid their numerous enemies. It is, as we com- 
menced by remarking, “a struggle for existence,” in 
which the weakest and least perfectly organized 
must always succumb. 
The Abundance or Rarity of a Species dependent upon 
its more or less perfect Adaptation to the Con- 
ditions of Existence. 
It seems evident that what takes place among the 
individuals of a species must also occur among the 
several allied species of a group,—viz., that those » 
which are best adapted to obtain a regular supply 
of food, and to defend themselves against the attacks 
of their enemies and the vicissitudes of the seasons, 
must necessarily obtain and preserve a superiority 
in population ; while those species which from some 
defect of power or organization are the least capa- 
ble of counteracting the vicissitudes of food-supply, 
&e., must diminish in numbers, and, in extreme 
cases, become altogether extinct. Between these ex- 
tremes the species will present various degrees of 
capacity for exsuring the means of preserving life; 
and it is thus we account for the abundance or rarity 
of species. Our ignorance will generally prevent us 
from accurately tracing the effects to their causes; 
but could we become perfectly acquainted with the 
D 
