INDEX. 



Timiriazeff, on theory of chlorophyll- 

 function, 156, 254, 257 



Tip of root, irritability of, 467, 474, 

 479, 492 



Tissue, definition of, 10 



Tissue-tensions, 342, 405 



Todea Africana, apogamy of, 601 



Tollens, on aery 1 colloid, 31 



Tonic influence, 371; of heat (thermo- 

 tonus), 377, 577 ; of light (phototonus), 

 380, 392, 573 



Torsion, 353, 510; homodromous, 515; 

 antidromous, 515 



Torus, 625 



C. de la Tour, on effect of low tempera- 

 ture on yeast, 272 



Traction, effect on growth, 349, 413 



Tradescantia, hairs of, streaming of 

 protoplasm in, 297, 524 



Tragopogon orientate, light-position of, 



43 1 



Transpiration, 72, 103, 576; relation of, 

 to absorption by roots of salts and 

 water, no, 115; to growth, 576; to 

 humidity of air, 108; to light, 109, 

 576 ; to mechanical disturbances, 112, 

 576; to negative pressure, 117; to 

 temperature of air, 108 ; to tempera- 

 ture of soil, 109; to tissue-tensions, 

 406; to age of leaf, 107 



Transpiration - current, 96 ; passage 

 through wood, 97 ; rate of, 100 



Traube, on artificial cells, 42 



Treub 



on embryo of Orchids, 178 

 on hook climbers, 411 



Treviranus, on erythrophyll, 266 



Trinchinetti, on absorption of salts by 

 water-plants, 60 



Tropaolum majus^ dorsiventrality of, 

 425, 429 



Tubes corpusculiferes (Dutrochet), 586 



Tulasne, on reproduction of Pyronema 

 (Peziza), 621 



Turgidity, 40; daily period of, 569; 

 factors of, 42, 562; recovery of, 567; 

 relations of, to growth, 335, 342; 

 relation to tissue tensions, 406 

 of etiolated internodes, 391 



Tussilago farfara, pendent position of 

 buds, 455 ; change in geotropism of, 



459 



Twining, causes of, 508; direction of, 

 (Fig- 54), 5i6 



Twining stems (Fig. 54), 516; irrita- 

 bility of, 511 



Tyloses (Fig. 40), 350 



Ty rosin, 221 



Ulothrix, 522, 524; phototaxis of zoo- 



spores of, 523; reproduction of (Fig. 

 65), 606 

 Ulvacese, 9 

 Uncaria ovalifolia, hooks of (Fig. 47), 



412 



Undulating nutation, 368 

 linger 



on lenticels, 72 



on loss of water by transpiration, 

 104, 105 



on movements of stamens of Cy- 

 narese, 559 



on periodicity of transpiration, 114 

 on branching of roots in soil, 52 

 on root-pressure, 92 

 on structure of stamens of Berberis 

 and Mahonia, 533 



on structure of stamens of Cy- 

 nareae, 533 



on transpiration, as affected by 

 stomata, 107 



on the velamen of Orchids, 50 

 (Fig. 12) 



Unorganised ferments, 188; action of, 

 191; classification of, 189; influence 

 of temperature on, 192; preparation 

 of, 193 



Uredinese, life-history of, 634; repro- 

 duction of, 624 

 Uredospores, 603 

 Urich 



on absorption of nitrates by plants, 

 127 



on glutamin in beetroot, 171 

 Urtica macrophylla, cystolith from (Fig. 



34). 249 



Ustilaginese, conjugation of, 618; life- 

 history of, 634 



Vacuoles, 13, 28; formation of, 28; 

 pulsating, 522, 558 



Variability: hereditary, 676; origin of, 

 676; of cultivated plants, 652, 675, 

 679; of hybrids, 676; promoted by 

 sexual reproduction, 676 



Variation, 652, 675 



Varieties, 652 



Vascular Cryptogams, isosporous, 603 



Vascular plants, heterosporous, 603 



Vaucheria, 8; heliotropism of, 428, 

 441; reproduction of, 610 



Vegetative reproduction, 597; relation 

 of to life-history, 635 



Velamen, 50 (Fig. 12) 



Velten 



on circulation of protoplasm, 524 

 on electricity, 323 



Ventral canal-cell, 641 



Verbascum, want of heliotropic irrita- 

 bility, 431 



