mo and.

Placentata.

Plagiaulax, Falconer on.

Planaria.

Planorbis, Hyatt on genesis of species of.
-P. multiformis, graduated forms of.

Plantago, Ludwig's observations on.
-Darwin on.

Plants, change in animals compared with change in.
-comparison between high and low as regards resistance to injurious
conditions.
-contractility of.
-difference between animals and.
-distribution of.
-fossil.
-of Madeira.
-morphological characters.
-resemblance to animals.
-Saporta's work on fossil.
-small proportion preserved as fossils.
-splendid for helping belief in Natural Selection.
-thorns in.
-wide range as compared with animals.
-Darwin's interest in movements of.
-Darwin on physiology of.
-disease in.
-effect of stimuli on.

Plas Edwards.

Plasmodiophora, action on cruciferous roots.

Platanthera, H. Muller on.

Plato, comparison between plants and man in his "Timaeus."

Platysma myoides, contraction during terror.
-Darwin's error concerning.

Playfair, Lord.

Pleistocene Antarctic land, plants derived from.

Pliocene, Falconer on mammal from the.

Plovers, protective colouring of.

Plumage, immature and adult.

Plumbago, Darwin's experiments on.
-said to be dimorphic.

Podostemaceae, fertilisation of.

Poisons, natives of Australia injured by vegetable.
-absorption by roots of.
-effect of injection into plants.

Polar bear, modification of.

Polar ice-cap, Darwin on the.

Polarity, E. Forbes' theory of.

Pollen, direct action of.
-experiments on.
-time of maturity in Eucalyptus and Mimosa.
-mechanism for distribution in Martha.
-Miyoshi's experiments on tubes of.

Polyanthus, crossing in.

Polyborus Novae Zelandiae, in Falkland Islands.

Polydactylism, and inheritance.

Polyembryony, in Coffea and Pachira.

Polygala.
-P. vulgaris, variation of.

Polygamy, in birds.
-in Machetes.

Polygonum, germination of seeds found in sandpit.

Polymorphism, Darwin and Hooker on.
-Wallace on.

Polytypic genera, variation of.

Pontederia, heterostylism of.

Pontodrilus, Lankester on.

Poplar, Heer on fossil species.

Popper, J., letter to.

Poppig, on civilisation and savagery.

Poppy (corn-), indigenous in Sicily.

Porpoises, Flower on.
-freshwater.
-Murray on.

Portillo Pass.

Porto-Santo, land-snails of.
-plants of.

Positivism, Huxley's article in "Fortnightly Review" on.

Poso