INDEX. 



345 



309 ; explained, 285 ; oiigin of, 



300 

 Homomorphic conditions, 203 

 Homostyled, flowers, explained, 203 ; 



fonn.s of Aurictila, 208 ; of JPrimula 



Sitiensis, 209 

 Hooks of Uncaria, (fig. 46) 156 

 Hypertrophy, in animal Icingdom, 88 ; 



cause of, 51, 88; effects of, in 



unions, 86, 87 ; form, a cause of, 



105, seqq. ; 116, seqq. ; in Orchids, 



87 ; of placentas, 307 



I 



Hlegitimate, or homomorphic unions 

 206 



Impatiens, secretive stipules of, (fig. 

 43) 140 



Impregnation, a form of nutrition, 

 250 



Inconspicuous flowers, 251, seqq.; 

 anemophilous, 265 ; due to degene- 

 racy, 251, seqq. ; origin of, 282 ; 

 self-fertilising, 253, seqq. 



Insects, origin of species by agency 

 of, 329 ; relative proportion of, in 

 regular and irregular flowers, 102, 

 103, 314; visitors to Composite, 

 315 



Irregularity, origin of, 103 



Irritability. See Ant-plants, Appen- 

 dages, Form, Protoplasm, Zygo- 

 morpbism. 



Laws, of alternation, 41 ; of colour, 



174 ; of superposition, 41 

 Leaf, cabbage, excrescences on, 307 ; 



of Coniferce, adnate and free, 84, 



85 ; opposite and verticillate, 9 ; 



transition from opposite to verti- 



ciUate, (fig. 2) 11, 17, 18. See 



Phyllotaxis. 

 Leaf-traces, of Arabis albida, (fig. 7) 



39 ; compared with floral, 40 



Liber-fibre, origin of, 250 



Light, and cell-division, 154 ; in- 

 fluences of, on leaves, 154; on 

 roots of Ivy, 155 ; on nucleus, 154 ; 

 and sleep of calyx and corolla, 155 



Lysimachia, anatomy of floral re- 

 ceptacle of, (fig. 19) 77 



M 



Mechanical forces, action on boughs, 

 125; on corolla, 126; on pear 

 growth, 124; on stamens, 81, 82, 

 126 ; tissues, formation of, by, 155, 

 seqq. See Irritability. 



Metamorphosis, of bracts, 286 ; of 

 calyx, 288; of corolla, 292, 302; 

 of flowers, 285, 295 ; of pistil, 295 ; 

 of stamens, 292, 298 ; of tentacles 

 ot Drosera, 307 



Movements, in corolla, 160 ; of fila- 

 ments, 159, 161, 162; of pistil, 

 162; of stamens, 162; of staminode, 

 161 ; of stigmas and styles, 159, 

 162 



N 



Narcissus cemuus, unstable hetero- 

 stylism of, 121 



Natural selection, difficulties of, 333 ; 

 forms of, 330, seqq. ; insufficient 

 as a cause, 335. See Selection. 



Nectaries, 140, seqq. ; and adelphous 

 stamens, 58 ; irritation, an origin 

 of, 141, 143 ; and pollination, 148 ; 

 position of, 140, seqq. ; staminal in 

 Atragene, (fig. 44) 141 ; stipular 

 in Impatiens, (fig. 43) 140 



Nepenthes, origin of pitcher of, 146 



Nucleus, effect of electrical irritation 

 on, 154, of light on, 154 ; of pollen- 

 tube, effect of, 250 



Numbers, illustrations of special, 25- 

 38 ; origin of, 9 ; principle of 4, 7 



