Breeding Animals With Separate Sexes

I have seen it gravely remarked, that it was most fortunate that the strawberry began to vary just when gardeners began to attend closely to this plant. No doubt the strawberry had always varied since it was cultivated, but the slight varieties had been neglected. When there appeared, aided by some crossing with distinct species, those many admirable varieties of the strawberry which have been raised during the last 30 or 40 years. In the case of animals with separate sexes, facility in preventing crosses is an important element of success in the formation of new races. Wandering inhabitants of open plains rarely possess more than one breed of the same species. Pigeons can be mated for life, and this is a