The Variation of Animals and Plants Under Domestication, Volume II (of 2)

by Charles Darwin

Instincts, defective, of silkworms, i. 304.

Interbreeding, close, ill effects of, ii. [114]-[131], [175].

Intercrossing, of species, as a cause of variation, i. 188;

natural, of plants, i. 336;

of species of Canidæ and breeds of dogs, i. 31-33;

of domestic and wild cats, i. 44-45;

of breeds of pigs, i. 71, 78;

of cattle, i. 83;

of varieties of cabbage, i. 324;

of peas, i. 326, 329-330;