6) Struggle For Life Most Severe Between Individuals And Varieties Of The Same Species [Back to Contents ] [On To End ] 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.
(they; come; into competition with each other)
they
come
into competition with each other