674 



BOTANY OF THE LIVING PLANT 



Digestive glands of Drosera, 240 (Fig. 



166). 

 Digestive tract, in mycorrhiza, 231 



(Figs. 159, 160). 

 Digitalis purpurea, Foxglove, 644. 

 Dimorphism, of Primrose, 640 (Fig. 



492). . 



Dioecious, where staminate and pistil- 

 late flowers are borne on different 



plants, 301. 

 Dioecism, in Willow, 336, 619 (Figs. 



467-469) ; by abortion in Lychnis 



dioica, 271 (Fig. 194). 

 Dionaea, motile leaf- traps of, 165 



(Fig. 100). 

 Dioscorea, 607. 

 Dioscoreaceae, embryology of, 314 



(Fig. 233). 

 Diplobiontic Algae, 546, 556. 

 Diplococcus, 452. 

 Diploid, having double the typical 



number of chromosomes (2x), as 



shown by each nucleus on division ; 



this is characteristic of the sporo- 



phyte, 308 ; in Green Algae, 375 ; 



in Ferns, 457. See Chap, xxxiv. 

 Diplostemonous, where the stamens 



are twice as many as the petals, 



267. 

 Disaccharides, 123. 

 Disc-florets, of Compositae, 648 (Fig. 



500). 

 Discomycetes, 425 (Fig. 322), 428. 

 Disease, mortal, 235 ; epidemic, 396. 

 Dispersal of seeds, 323. 

 Dissolved substances, entrance of, 



Distal branching of shoot, 348. 



Divergence, angle of, in leaf arrange- 

 ment, the angle between the median 

 planes of successive leaves, 204 

 (Fig. 137). 



Division of nucleus, somatic (mitosis), 

 562 (Figs. 428, 429) ; tetrad-division 

 (meiosis), 563 (Figs. 430, 431). 



Dock, straight ovule of, 303 (Fig. 221). 



Dodder (Cuscuta), parasitism of, 223 

 (Fig. 151) ; suckers of, 225 (Fig. 



152). 



Dog Rose, 634. 



Dog's Mercury (Mercurialis) , 113. 



Dominant, that one of a pair of unit 

 characters which remains apparent 

 in all the offspring of the first cross, 

 e.g. tallness in Peas, 570 (Fig. 



435)- 



Dormancy of seed, 140. 



Dorsiventral symmetry, where an 

 organ or shoot develops unequally 

 on two sides, in relation to gravity, 



light, etc., 205 ; of lateral branches, 

 186 ; of rhizomes, 206, 207. 



Double fertilisation, in Helianthus, 

 306-308 (Fig. 227). 



Doubling of flowers, 268. 



Dracaena, secondary thickening of, 

 67 ; raphides of, 54 (Fig. 33) ; leaf 

 arrangement {irsch) in, 205. 



Dressing of seed-grain, 441. 



Dried fruits, analyses of, 657. 



Drosera, motile tentacles of, 164 

 (Fig. 99) ; carnivorous habit of, 

 239 (Fig. 166) ; digestion in, 240. 



Drought, physiological, 211. 



Drupe, a fruit with succulent middle 

 layer of the pericarp, and stony 

 inner layers, 329 (Fig. 253) ; 635 



(Fig. 487). 



Dryopteris filix-mas, Chapter xxxi., 

 p. 481 ; leaf of, 482 (Fig. 373) ; 

 stock of, 484 (Fig. 374) ; vascular 

 system of, 484 (Fig. 374), 486 (Fig. 

 376 a) ; meristele of, 488 (Figs. 

 377, 378) ; leaf-structure of, 491 

 (Fig. 381) ; sorus of, 482 (Fig. 373), 

 495 (Fig. 387) ; sporangium of, 

 496-498 (Figs. 388-390) ; prothal- 

 lus of, 499-50 1 (Figs. 391-393)- 



Dryopteris pseudo-mas, v. cristata, 

 apospory and apogamy in, 509 

 (Fig. 404). 



Dry Rot fungus (Merulius), 442. 



Dry weight as growth index, 145. 



Duration, biology of, 194. 



Dwarfs, 570, 601. 



Dwarf-males, of Oedogonium, 367 

 (Fig. 271). 



Earthworms, 98. 



Eating Pea (Pisum sativum), used in 

 Mendel's experiments, 570. 



Ecballium, squirting fruit of, 324. 



Ecology, the study of plants in rela- 

 tion to their surroundings, 3. 



Economy of material, 180. 



•Ectocarpales, 378, 383. 



Ectocarpus, gametes of, 381, 383 ; 

 siliculosus, gametes of, 381 (Fig. 

 285) ; sex distinction in, 386. 



Ectotrophic mycorrhiza, where the 

 fungus lives outside the tissues of 

 the host, 228 (Figs. 156, 157). 



Edelweiss, hairy covering of, 74. 



Egg-apparatus, a group of primordial 

 cells at the micropylar end of 

 the embryo-sac, consisting of two 

 synergidae and the ovum, 295 

 (Fig. 216), 299 (Fig. 219). 



Egg, or ovum, 332, 353 ; protection 

 of, in Land Plants, 455. 



