——, fleshy, on sea-shores, [132].
——, fresh-water, distribution of, [386].
——, low in scale, widely distributed, [406].
Plumage, laws of change in sexes of birds, [89].
Plums in the United States, [85].
Pointer dog, origin of, [35].
——, habits of, [213].
Poison not affecting certain coloured animals, [12].
——, similar effect of, on animals and plants, [484].
Pollen of fir-trees, [203].