358 INDEX. 



rally whatever is fluid and sufficiently attenuated, 16 — their 

 property of throwing off secreted, deleterious, or superfluous 

 matter, 19 — necessity of their advancing into fresh soil, 20 — in 

 general have no buds, 20 — of some species, their power o! 

 forming adventitious buds, 20 — their fitness for propagation 

 depends on their power of forming adventitious buds, 20 — 

 effects of their being situated in a widely different temperature 

 from that of the branches, 49 — their action reciprocal with 

 that of the leaves, 49 — bad effects of their being deeply 

 covered by soil, 105 — their deep penetration into cold soil, a 

 cause of canker, 106 — are naturally placed in a higher mean 

 temperature than branches and leaves, 107 — instances of their 

 production by leaves, 190 — emitted into the air, 198 — are 

 formed by the action of leaves, 199 — may be grafted, 225 — 

 renovation of, 248 — pruning of, 249, 29 S — their deleterious 

 excretions, 270 — their slender power of selecting food, 270 — 

 their direction in pots, 272— matted, 806 — bruised, 292 — of 

 trees retain the powers of life longer than branches, 19. 

 Rose, double yellow, expansion of its flowers, 84. 



S. 



Saddle-grafting, 219. 



Salts, certain of them enter into the composition of the food of 

 plants, 18. 



Sand, employed in propagation by cuttings, 203. 



Sap-wood, its mode of formation, 27. 



Sap, its constituents, 32 — its transmission through the stem, 82 — its 

 changes during the course of its circulation, 82— rof plants may 

 be made to deviate from its usual course, 33 — cause of its flow, 

 86 — motion of, different from its flow, 36 — its ascending and 

 descending currents communicate with different systems of 

 veins in leaves. 36 — ascending, its force, 47 — derangement of its 

 course, 49 — accumulation of, 72 — its circulation affected by 

 motion communicated to plants by wind, 157 — may be com- 

 pelled to organise itself externally as roots, 208 — direction 

 given to, by pruning, 241 — its return obstructed by ringing, 

 252 — an inspissated state of, produced by a dry atmosphere, 325. 



Saturation, hygrometrical, 127. 



Scarring the centre of bulbs, 210. 



