affinity of the tissues for special organic substances, ii. [380].

Pallas, on the influence of domestication upon the sterility of intercrossed species, i. 31, 83, 193, ii. [109];

hypothesis that variability is wholly due to crossing, i. 188, 374, ii. [250], [264];

on the origin of the dog, i. 16;

variation in dogs, i. 33;

crossing of dog and jackal, i. 25;

origin of domestic cats, i. 43;

origin of Angora cat, i. 45;

on wild horses, i. 52, 60;

on Persian sheep, i. 94;