Parkin, J. and E.A.N. Arber, on the origin of Angiosperms.
Peckham, Dr and Mrs, on the Attidae.
Philosophy, influence of the conception of evolution on modern.
Phylogeny, embryology as a clue to. --Palaeontological evidence on.
Physiology of plants, development of.
Pickering, spectroscopic observations by.
Plants, Darwin's work on the movements of. --geographical distribution of. --Palaeontological record of fossil.
Polymorphic species. --variability in cereals.