sexual differences in, ii. [73];
influence of crossing or segregation on, ii. [86], [95]-[96], [102]-[103];
interbreeding of, ii. [119]-[120];
effect of nourishment on the fertility of, ii. [111]-[112];
diminished fertility of, under certain conditions, ii. [161];
unconscious selection of, ii. [213];
natural selection in breeds of, ii. [224], [225], [227];
reduction of bones in, ii. [242];
individual differences of, ii. [251];
local changes in the fleece of, in England, ii. [278];