Primula, Darwin's paper on, i. 218
"Principles of Geology," Lyell's, i. 135, ii. [5]
"—— of Psychology," Spencer's, i. 123
"—— of Sociology," Spencer's, i. 126
Proctor, R.A., i. 263; "Expanse of Heaven," ii. [180]
"Progress and Poverty," Henry George's, i. 317, 318, ii, [143]
Protection, principle of, i. 140, 177, 184, 186, 189, 192, 199, 205, 212 et seq., 214 et seq., 220, 221, 222, 223, 224, 226 et seq., 235-6, 252, 256, 257-9, 270, 291, 299-300
(see also Coloration, protective, and Mimicry)
"Protective Resemblance," Wallace's, i. 214
"—— Value of Colour and Markings in Insects," ii. [38]
Protoplasm, origin of, Sir W. Thiselton-Dyer on, ii. [96]-7