INDEX 



447 



phloem, 65. 



phosphorescent organs, 336. 

 phosphorus, 22, 71. 

 photosynthesis, 30, 31. 

 phyla, "226. 



Pliyllopteryx eques, 341, Fig. 174. 

 phylogenetic tree, 229. 

 phylogeny, 229. 



,, and classification, 230, 



231, Fig. 87. 

 ,, ontogeny, 265, 279, 



Fig. 131. 



,, Erasmus Darwin on, 372. 

 physical basis of life, 7. 



,, conditions of earth, changes 



in, 327. 

 physiological selection, 418. 



unit, the cell, 6$. 

 Phytoflagellata, colony formation, 40, 



42. 

 evolution of sex, 89 



91. 



Pieriiiae, 345. 

 pig, feet, 241, Fig. 98. 

 pineal eyes, 258 260, Figs. 114 116. 



gland, 11, 260. 

 pin-eyed flowers, 356. 

 pistil, 106. 



Pisinn sativiim, varieties, 196. 

 pitcher plants, 262. 

 1'itliecanthropus erect us, 423. 

 pituitary body, 408. 

 placenta, 270. 

 placenta! mammals, appearance of, 



302. 



Playianthiis betulinus, 417. 

 PlagiaulacidjB, 302. 

 Plagiaulax, 302, Fig. 148. 

 I'ldnema pogyei, 346. 

 plankton, 322. 

 plants, compared with animals, 34, 35. 



dispersal of, 321. 

 plasma, 51. 

 plasmodia, 67. 

 plasniogamy, 128. 

 plasticity of organisms, 335. 

 plastids, 32. 

 plastogamy, 128. 

 Platypus (see Oniithorhynchus). 

 Pleistocene Epoch, 284. 

 plerorne, 50. 



Plesiosauria, 236, 244, 297. 

 J'lesiosaiirus macrocep /talus, Fig. 141. 

 Pliny, 262. 

 Pliocene Epoch, 284. 

 Pliohippus, 310, 311, Figs. 153, 158. 



ploughshare bone, 305. 



plumage of birds, 349. 



plumcots, 204. 



pluteus larva), 275, 276, Fig. 127. 



polar bodies, 133, 135, 139, 145, Figs. 



35, 65, 68. 



pole-cell, in insect egg, 130. 

 pollen, collection of, 355. 

 ,, grains, 106, 107. 

 sacs, 107. 

 tube, 108. 

 pollination, 110, 111. 



,, adaptations for, 35 1363. 

 pollinia, 361. 



polyanthus, pollination, 356. 

 poly dactyli sin, 149. 

 polymorphic colony, 119. 

 polymorphism in Papilio, 346, Fig. 



177. 



polype, fresh water (see Hydra). 

 Polypodium, archegonium, Fig. 52. 

 Poly/oa, dispersal, 327. 

 population, Buff on on, 368. 



,, Charles Darwin on, 386. 

 ,, Lamarck on, 381. 

 Wallace on, 389. 

 porpoises, convergence in, 248. 

 Portunus, 247, Fig. 102. 



larva, Fig. 128. 

 postaxial, 238. 

 potential energy, 7. 

 Poulton, E. B., 336, 337, 346. 

 preaxial, 238. 



Pre-Cauibrian Epoch, 284, 285. 

 pre-formation in development, 163. 

 prehension, organs of, 256. 

 prepotency, 353, 358. 

 presence or absence hypothesis, 207. 

 Primary Era, 284, 285. 

 Primates, 301, 303. 

 primordia, in germ plasm, 206. 

 primordial germ cells, 113 (see also 



germ cells, origin). 

 ,, utricle, 62, 95. 



Primula, fertilization, 356358. 

 priority in nomenclature, 227. 

 Proboscidea, evolution, 312 314, 



Fig. 159. 

 proboscis, of bee, 354, Fig. 179. 



,, butterflies and moths, 



354. 



elephants, 256. 

 , , insects, Erasmus Darwin 



on, 373. 

 ,, mutual adaptation, 



414, 415. 

 procryptic coloration, 337 342. 



