Struggle for Life most severe between Individuals and Varieties of the same Species As the species of the same genus usually have, though by no means invariably, much similarity in habits and constitution, and always in structure, the struggle will generally be more severe between them, if they come into competition with each other, than between the species of distinct genera.
(Struggle for Life most severe between Individuals and Varieties of the same Species As the species of the same genus; have; T:usually) (they; come; into competition with each other)
Struggle for Life most severe between Individuals and Varieties of the same Species As the species of the same genus they
have come
T:usually
into competition with each other