INDEX. 



605 



Trees, longeTity of, 40, 41 



nodules in the bark of, 44 



remarkable instances of vitality in, 



260 

 Trifacial orange, 360 

 True sap wholly generated in the leaves, 



370 

 Tubers, 43 

 instances of, formed by flowers, 85 



propagation by, 473 



Undeeoeoukd climate, 137 

 Unisexual plants, effects of temperature 

 on, 108 



Valleys, general coldness of, compared 

 with higher ground, 200 



• their liability to sudden cold, 



200 

 Van Hall, his observations on the in- 

 fluence of leaves in increasing the 

 trunks of trees, 71 

 Varieties and species, in their intrinsic 



qualities the same, 476 

 Varieties are usually far more disposed 

 to mix than species, 499 



early and late, influenced by 



soil, 466 



how continued, 485 



means of fixing them, 464 



owe theirorigiu to some special 



circumstance, 479 

 Vegetable, cells, have their own special 



power of secretion, 344 

 ■ excitability, 295 



irritability, 11 



life, ; principal circumstances 



connected with, 6 

 respiration, Mr. Pepy's ex- 

 periments on, 61 

 Vegetation in forcing houses, mode of 



resting it, 611 

 Veins, 56 



of leaves consist of two systems, 56 



Ventilation, 213 



advantages of, 215 



^— by drains, 226 



injurious effects of, 222 



in winter, 



Vine borders, effect of concreting, 144 



mode of concreting, 146 



precautions for draining 



of, 170 



countries, temperature of, 515 



effects of grafting, 304 



grafting of, 352 



in Greece, 350 



its necessity, 214 



just as necessary in winter 



as in summer, 217 



Knight's remarks and ex- 

 periments on, 216, 225 



practice of, 224 



Williams of Pitmaston's 



mode of, 225 



Vine, application of potash to, 654 



borders, formation of, 146 



artificially warmed, 143 



mode of increasing from eyes, 264 



pruning, diagram illustrative of, 72 



remedy in cases of bleeding, 364 



soil in which it arrives at the 



greatest perfection, 144 



warmth of soil for, 136 



cause of earlyforoed,notsetting, 140 



Vital force, 7 



in plants decomposes water, 60 



its presence exemplified in 



fresh-water confervas, 10 



manifestedby pollen tubes, 10 



proofs of, 8 



of vegetation, 60 



Vital functions of plants, 177 

 Vital points on the stem, formation of, 43 

 Vitality explained, 12 

 in seeds, causes of its destruc- 

 tion, 104 



in plants, evidence of, 11 



remarkable instances of, in 



plants, 259, 261 

 Vital principle, its presence admitted, 

 enables us to elucidate 

 many things that are 

 obscure in vegetable 

 physiology. 111 

 stimulated by heat, 15 



universal, 12 



Walls, effects of blackening, 199, 423 



impoi*tance of, in improving 



the flavour and hastening the 

 maturation of the fruit, 423 



importance of, with regard to 



shelter, 186 

 Walnut, propagation of, by budding, 310, 

 337 



by grafting, 338 



Wardian cases, fault of, 222 



unfit for cultivation, 221 



useful for sending live 



. plants by sea, 257 

 Water, a copious supply of, increases the 

 size, but diminishes the flavour 

 ofthefrait, 166 

 a vehicle by which oxygen is sup- 

 plied during the process of 

 germination, 14 



circulation and cooling of, 162 



conduces to germination, 15 



effects of immersing roots in, 168 



