INDEX. 



347 



tity, reduction of, 273 ; of self- 

 fertilising plants, 254 



Pollen-tube, effects of, 166, 167; 

 irritation due to, 164, seqq. ; in 

 Orchids, 166, seqq. ; in Oxalis, 260 ; 

 in Verbascum. 168 ; in Violets, 258 ; 

 in Willows, 170 



Pollination and nectaries, correlation 

 between, 148 



Polygamous flowers and environment, 

 242 



Pressure, effects of mechanical, 101, 

 seqq., 116, seqq., 123, seqq., 156, 

 seqq. ; resistance to, by cell-wall, 

 127 



Primine and secundine, foliacious, 306 



PrimulacecB, free-central placenta of, 

 interpretation of, (figs. 18, 19) 76, 

 77 



Principles, general, 1 ; of variation, 4 



Protandry, cause of, 198 ; explained, 

 198 ; illustrations of, 191, seqq. ; 

 in Echium, (fig. 20) 82 ; and self- 

 fertilisation, 272, 273, seqq. 



Protogyny, anemophily as a cause of, 

 200,' 269; causes of, 199, seqq.; 

 emergence and order of develop- 

 ment of flowers with, 195; ex- 

 plained, 198 ; inconspicuousness of 

 many flowers with, 195 



Protoplasm, common to animal and 

 vegetable kingdoms, and pheno- 

 mena same in both, 147 ; irrita- 

 bility of, to electricity, 152, to 

 temperature, 153, to touch, 153, 

 seqq. ; origin of species due to 

 responsive powers of {see Origin of 

 Species) ; transmission of effects of 

 irritation by continuity of, 163 



R 



Ranunculaceoe, arrangement in, illus- 

 trations of, 21 ; symmetry in, illus- 

 trations of, 21 



Receptacle, floral, anatomy of, in 

 Cruciferce, (fig. 6) 32; in Helle- 

 bore, (fig. 12) 64; in Ivy, (fig. 14) 



68 ; in Lysimachia, (fig. 19) 77 ; 

 in Pelargonium, (fig. 13) 65 ; in 

 Primula, (fig. 19) 77 



Receptacular tube, 89, seqq. ; ana- 

 tomy of, in Alstroemeria, (fig. 30) 

 97 ; arrested conditions in, 91, 100 ; 

 with calvx foliaceous, (fig. 67) 

 289 ; of Cherrv, (fig. 29) 97 ; of 

 Cotoneaster, (fig. 22, 6) 90; of 

 Fuchsia, (fig. 27) 94 ; of Galanthus, 

 98; of Hawthorn, (fig. 25) 93; 

 interpretation of, 86 ; morphologi- 

 cal investigations of, 90 ; of Mus- 

 scenda, (fig. 68) 290 ; of Ka7'cissus, 

 98 ; of Orchids, (fig. 23) 92 ; of 

 Pear, 86, (fig. 22, a) 90, (fig. 26) 

 94; o£ Prunus, (fig. 28) 95; of 

 Rose, (fig. 24) 93 ; teratological in- 

 vestigations of, 92 ; views of, 89 



Regularity, acquired, 128 ; explained, 

 5 ; observations on, 101 ; position 

 of flowers with, 101 ; Tingidce as 

 causing, 130. See Peloria. 



Resupination, origin of, 107 



Roots, adhesive, of Orchids, (fig. 42) 

 137; origin of hairs on, 137; of 

 Ivy, effects of light on, 155 



Rudimentary organs, 283 



Salvia, cleistogamous species, 262, 

 263; cords of sepals of, 55; fila- 

 ments of, 268; self-fertilising spe- 

 cies, 261 



Scent, absence of, in self-fertilising 

 flowers, 254 



Secretive tissues, as conducting, 164, 

 seqq.; irritation as a cause of, 142 ; 

 of milk, 147 ; as nectaries, 140, 

 seqq. ; in Nepenthes, 146 ; origin 

 of, 141 



Secundine, and primine, foliaceous, 

 306 



Seeds, character of, for double flowers, 

 299 ; number of, compared with 

 carpels, 21, 278, with stamens, 

 275 ; proportion of, to seedlings in 

 Orchids, 280 



