362 INDEX. 



tions of a plant, 49 — limits of, endurable by plants, 80 — limit 

 of, below which plants will not grow, 81 — effects of one lot 

 high on plants, 81 — unnaturally low, its effects, 83 — relatively 

 high, conjoined with dryness, favours the formation of secre 

 tions, 83 — at which different fluids become frozen, 85 — its laws 

 with respect to its influence on vegetation, 87 — its alternations 

 necessary to plants, 88 — of the earth at various places imnitvii 

 ately below the surface, 91 — effects of its diurnal alternations, 

 87 — effects of its annual alternations, 88 — of the earth, 90, 93 — 

 at various places, comparatively with that of the atmosphere, 

 91 — at various depths, 92 — of the hottest and coldest months at 

 various places, 100 — importance of insuring a proper one lor 

 plants, 108 — of soils, its important influence on vegetation, 108 

 — with regard to the direction of the wind, 130, 134 — of hot- 

 houses, its regulation, 142 — effects of a high one at night in hoL- 

 houses, 145 — effects on pollen of one too low, 171 — which grain 

 will bear, 181 — seasons of extreme, 320 — uniform, 320 — low. 

 with much light, its effects on the sap, 325 — of plant houses, ne- 

 cessity of 16wering it during the night, 328 — diurnal extremes 

 of, 828. 



Tissue, general distension of, in the embryo state of roots, 9 — general 

 distension of, in roots growing in air and water, 13 — its hyero- 

 metrical force depends on the action of capillary tubes, 16. 



Tissue, its first formation requires nitrogen, 18 — disorganisation of, 

 117 — impermeability of, induced by training, 265 — cellular, is 

 the component of the first rudiments of the stem, 21. 



Tongning, 217. 



Training, 257 — on a horizontal plane, bad effects of, 257 — its effects 

 on the circulation of the juices, 259 — pendulous, 260 — its disad- 

 vantages, 265. 



Transplanted trees, their pruning, 248 — languid from previous dry 

 ness, effects on, by the too rapid absorption of water, 294. 



Transplanting, 279 — its rationale, 281 — season for, 283 — of deciduous 

 trees, 280 — manner of performing the operation, 290 — prepara- 

 tion of old trees for, 291. 



Trees and shrubs, distinct parts of their bark, 26. 



True sap, wholly generated in the leaves, 252. 



Tubers, 29. 



