effects of disuse of parts in, ii. 299;
ears of, ii. 301;
correlations in, ii. 327;
white, buck-wheat injurious to, ii. 337;
tail of, grafted upon the back, ii. 369;
extinction of the older races of, ii. 426.
PIMENTA, ii. 91.
PIMPERNEL, ii. 190.
PINE-APPLE, sterility and variability of the, ii. 262.
PINK, Chinese. 322.
PINKS, bud-variation in, i. 381;
improvement of, ii. 216.
_Pinus pumilio_, _Mughus_, and _nana_, varieties of _P. sylvestris_, i.
363.
_Pinus sylvestris_, i. 363, ii. 310;
hybrids of, with _P. nigricans_, ii. 130.
PIORRY, on hereditary disease, ii. 7, 78.
_Pistacia lentiscus_, ii. 274.
PISTILS, rudimentary, in cultivated plants, ii. 316.
PISTOR, sterility of some mongrel pigeons, i. 192;
fertility of pigeons, ii. 112.
_Pisum arvense_ and _sativum_, i. 326.
PITYRIASIS versicolor, inheritance of, ii. 79.
PLANCHON, G., on a fossil vine, i. 332;
sterility of _Jussiaea grandifiora_ in France, ii. 170.
PLANE tree, variety of the, i. 362.
PLANTIGRADE carnivora, general sterility of the, in captivity, ii. 151.
PLANTS, progress of cultivation of, i. 305-312;
cultivated, their geographical derivation, i. 311;
crossing of, ii. 98, 99, 127;
comparative fertility of wild and cultivated, ii. 112-113;
self-impotent, ii. 131-140;
dimorphic and trimorphic, ii. 132, 140;
sterility of, from changed conditions, ii. 163-165;
from contabescence of anthers, ii. 165-166;
from monstrosities, ii. 166-167;
from doubling of the flowers, ii. 167-168;
from seedless fruit, ii. 168;
from excessive development of vegetative organs, ii. 168-171;
influence of selection on, ii. 199-201;
variation by selection, in useful parts of, ii. 217-219;
variability of, ii. 237;
variability of, induced by crossing, ii. 265;
direct action of change of climate on, ii. 277;
change of period of vegetation in, ii. 304-305;
varieties of, suitable to different climates, ii. 306;
correlated variability of, ii. 330-331;
antiquity of races of, ii. 429.
PLASTICITY, inheritance of, ii. 241.
PLATEAU, F., on the vision of amphibious animals, ii. 223.
_Platessa flesus_, ii. 53.
PLATO, notice of selection in breeding dogs by, ii. 212.
PLICA polonica, ii. 276.
PLINY, on the crossing of shepherd's dogs with the wolf, i. 24;
on Pyrrhus' breed of cattle, ii. 202;
on the estimation