310 



ESSAYS OF A BIOLOGIST 



Philosophy of life, unitary, 228. 



Pipit, 108. 



Plasticity, evolutionary, 133. 



, mental, 231. 



Play, in animals, 123. 



Poetry, 54. 



Polydaemonism, 247. 



Polytheism, 247, 



Possession, demoniac, 220. 



Power, external, i . 



, idea of in primitive 



races, 211. 

 Prayer, 218, 297. 

 Pressure, biological analogy with 



in evolution, 38. 

 Priests, 230, 299. 

 Progress, biological, 27, 87, 215, 



23i,253ff. 



, biology and idea of, 85. 



, history of idea, 8. 



, law of, 9. 



, in man, 48 ff. 



, mechanism of, 32, 



, rate of, 42. 



, spiritual, 53. 



Projection, psychological, 167, 



222, 279. 

 Propitiation, 297. 

 Protozoa, 17. 

 Prout, 215. 



Psycho-analysis, I54ff'., 170. 

 Psychology and science, 239. 

 Psychozoic period, 257. 

 Puberty, 149. 

 Purpose, 41, 215. 



Rate, of Evolution, 42, 260. 



, of living, 188. 



, of progress, and ethics, 



42. 

 Raven, 126. 

 Receptor organs, 2i. 

 Reinach, S., 237, 244. 

 Rejuvenation, 139. 

 Relativity, biological, 200. 

 Religion, and Science, 235. 

 , comparative, 221. 



Religion, definition of, 210, 244. 



, history of, 236, 247. 



, irrational, 290. 



, operation of, 284. 



, political importance of 



unity in, 302. 



, and reason, 290. 



, social aspects of, 301, 302. 



Religious experience, 222, 227, 



292. 

 Repression, 151, 229, 270. 

 Revelation, 218, 227, 244. 

 Ritchie, 91. 

 Ritual, 227, 244, 297. 

 Rivers, W. H., 155, 165, 166, 



210. 

 Roberts, Morley, 75. 

 Rooks, 127. 



Sacculina, 12. 



Sacrifice, 297. 



Sand, K., 139. 



Science, and nature, 235. 



Sculpture, 54. 



Sedge Warbler, 122. 



Selection, within organism, 95. 



, of ideas, 97. 



Self-regulation, 29. 



Sex, abnormalities of, 148, 149. 



, and beauty in organisms, 



100. 



, determination of, 137. 



, and education, 153, 157, 



162, 169. 



, evolution of, 133. 



Sex-chromosomes, 137. 

 Sex-difFerence, degrees of in 



various species, 144. 

 Sex-instinct, 59. 



, transformation of, 160. 



Sex-psychology, 156 ff. 

 Sex-reversal, experimental, 142. 

 Sexual instincts, activation of, 143. 

 Shakespeare, 67, 300. 

 Shapley, 177. 

 Sherrington, 70, 

 Sin, sense of, 277. 



