INDEX AND GLOSSARY 



557 



Digestive ferment, of Fungi, 406. 

 Digestive sae, the layer of cells which 



softens the outer-lying tissues for 



the passage outwards of the lateral 



root, 80 (Fig. 62). 

 Digestive tract, in mycorhiza, igg 



(Fig. 150), 200 (Fig. 151). 

 Digitalis purpurea. Foxglove, 530. 

 Dimorphism, of Primrose, 528. 

 Dioecious, where staminate and pistil- 

 late flowers are borne on different 



plants, 265. 

 Dioecism, in Willow, 300 (Fig. 245) ; 



by abortion in Lychnis dioica, 236 



(Fig. 184). 

 Dionaea, motile leaf-traps of, 132 



(Fig. 92). 

 Dioscorea, 493. 

 Dioscoreaceae, 494 ; embryology of, 



277 (Fig. 220). 

 Diploid, having double the typical 



number of chromosomes {2x), as 



shown by each nucleus on division ; 



this is characteristic of the sporo- 



phyte, 251 ; in Ferns, 348. 

 Diplostemonous, where the stamens 



are twice as many as the petals, | 



233- i 



Disc-florets, of Compositae, 533 (Fig. 

 442). 



Discomycetes. 436 (Fig. 368), 439. 



Disease, mortal, 203 ; epidemic, 406. 



Dispersal of seeds, 284, 287. 



Divergence, angle of, in leaf arrange- j 

 ment, the angle between the median , 

 planes of successive leaves, 171 

 (Fig. 129). 



Division of nucleus, somatic, 464 

 (Fig. 342) ; tetrad-division, 465 

 (Fig. 393). 469 (Fig. 394)- 



Dock, straight ovule of, 258 (Fig. 211), 

 267. 



Dodder (Cuscuta), parasitism of, 188, 

 I90 (Fig. 142) ; flowers of, 192 ; , 

 suckers of, 192 (Fig. 143). 



Dog Rose, 521. 



Dolichos Soja (Soja Bean), analysis 

 of, 542 ; origin of, 543. 



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, 473 (Fig. 393). 1 



Dorsiventral symmetry, where an 1 

 organ or shoot develops unequally 

 on two sides, in relation to gravity, 

 light, etc., 172 ; of lateral branches, 

 T73 ; of rhizomes, 173, 174. 



Double fertilisation, in lldianthus 



270 (Fig. 214 /;i.s), 272. 

 Doubling of flowers, 234. 

 Dracaena, secondary thickening of, 



56; leaf-arrangement (,",lli) in. 



171. 493- 

 Dressing of seed-grain, 430. 

 Dried fruits, analyses of, 344. 

 Drosera, motile tentacles of, 131 



(Fig. 91 bis) ; carnivorous habit of, 



207, 208 (Fig. 137) ; digestion in, 



207. 

 Drought, physiological, 178. 

 Drupe, a fruit with succulent middle 



layer of the pericarp, and stony 



inner layer, 293 (Fig. 240) ; 321 



(Fig. 429)- 

 Dry Rot Fungus (Merulius), 432. 

 Duration, biology of, 162. 

 Dwarf-males, of Oedogonium, 394 



(Fig. 331). 



Eating Pea, used in Mendel's experi- 

 ments, 473. 



Ecballium, squirting fruit of, 288. 



Ecology, the study of Plants in rela- 

 tion to their surroundings, 3. 



Economy of material, 138. 



Ectocarpeae, 377. 



Ectocarpus, secundus, gametes of, 

 381 (Fig. 322) ; siliculosus, gametes 

 of, 380 (Fig. 321), 461, 462. 



Ectotrophic mycorhiza, where the 

 fungus lives outside the tissues of 

 the host, 193 (Fig. 148). 



Edelweiss, hairy covering of, 63, 177. 



Egg-apparatus, a group of primordial 

 cells at the micropylar end of the 

 embryo-sac, consisting of two 

 synergidae and the ovum, 260 

 (Fig. 206), 262 (Fig. 209). 



Egg, production of in Land Plants. 



463- 

 Elasticity, limit of, that is the degree 

 of elongation which a strand or 

 wire will sutfer and recover its exact 

 length when the strain is removed. 



146, 147- 

 Elements, of Plant-food, 93- 

 Ehgulatae, those Lycopods which 



have no ligule, 318. 

 Elm, vascular bundle of, 47 (F"ig. 33) ; 



cambium of, 48 (Fig. 33) : bark of. 



54- 

 Elodea, Canadian weed, 10, 24. 40 ; 

 vegetative propagation of, 212. 



