CLIMBING PLANTS. 
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leaves by a twining plant. No doubt at first no leaf-climber 
depended entirely on its leaves, it was merely a twiner wbicb 
helped itself by its leaves. Gradually the leaves became more 
perfect, and then the plant could leave off the wasteful plan of 
growing spirally up a stick, and adopt the more economical and 
more effective one of pure leaf- climbing. 
Finally, from sensitive leaves were developed the marvellously 
perfect tendrils which can .perceive ^th of a grain, and can 
show distinct curvature within 25 " after being touched, ten- 
drils, with delicate sticky ends, or endowed with the power of 
moving towards the dark, or of creeping into little cracks, or 
with that mysterious sense of touch by which a tendril can 
distinguish a brother tendril from an ordinary twig, and can 
distinguish the weight of a drop of rain hanging to it from a bit 
of thread — in short, all the delicate contrivances which place 
tendril-bearers so eminently at the head of the climbing plants. 
There is only one more fact connected with the evolution 
of climbing plants which must be alluded to, namely, the 
curious way in which the representatives of the class are scat- 
tered throughout the vegetable kingdom. Lindley divided 
flowering plants into fifty-nine classes, called Alliances, and in 
no less than thirty-five of these climbing plants are found. This 
fact shows two things : first, how strong has been the motive 
power — the search after light — which has driven so many dis- 
tinct kind of plants to become climbers. Secondly, that the 
power of revolving, which is the first step in the ladder of 
development of the power of climbing, is present in an un- 
developed state in almost every plant in the vegetable series. 
