steuart's planter's guide. 271 



such as the aperture of a window, the plant shoots 

 forth towards the light, possibly in consequence 

 of the leaves inclining themselves to receive the ray- 

 on their superficies, and thus leading'the shoot in the 

 direction of the light. But this does not prove any- 

 straining or lengthening of the shoot to approach the 

 light ; and we ask, what do general opinion and Sir 

 Henry found their belief upon, of lengthening 

 growth and straining to approach the light ? 



Again, with regard to heat, we notice that plants, 

 particularly shoots from tubers, left to sprout in 

 cold, damp, confined cellars, throw out very long 

 stems, with wide spaces between the buds or leaves, 

 and that very long shoots always occur in confined 

 damp air — ^long in the ratio of the dampness and 

 confinement, whatever the degree of heat may be, 

 provided it exceed a little the vegetating point. Also 

 on the north side of hills, the trees have generally 

 longer stems than on the sun-ward side, although in 

 the former case, they are exposed to the northern 

 blast, while in the latter they bask in the sun. Has 

 the same kind of plant, in lower latitudes, longer 

 spaces between the leaves than in higher ? And if 

 it has not, is the cold, from greater evaporation, 

 sufficient to balance the superior heat of the cli- 

 mate ? 



I 



