Vegetal Evolution. 135 



fig, investigated by Darwin, which secrete a viscid 

 fluid by their rootlets and so stick and climb. 



(b) The hook climbers are the roses, brambles, 

 yellow bedstraw, etc., whose hooks are familiar. 



(c) The stem climbers are the hop and convolvulus. 

 Here the climbing is effected by " circumnutation " ; 

 the growing stem swings slowly round in the air, and 

 describes a complete circle in two hours and eight 

 minutes. If it strikes a support it continues to twine 

 until it clasps it. 



(d) The leaf-climbers are the gloriosa, clematis, 

 nasturtium, etc. These clasp supports with modified 

 tips of the leaves and with the leaf-stalk, circumnuta- 

 tion assisting. 



(e) The highest grade of climbing plants, the 

 tendril-bearers, comprise the passion-flower, grape- 

 vine, Virginia creeper, pea, sweet pea, sarsaparilla, 

 bignonia, cucumber, etc. When we see the tendrils, 

 like the feelers of a snail, searching in all directions 

 and clutching supports, we are inclined to accord to 

 these plants the attribute of consciousness and of 

 intention to seek for assistance ; but investigation 

 proves that the motion is only mechanical and auto- 

 matic. The tendril does not instantly clasp a support 

 as if it knew it for such ; yet that it does in its own way 

 know a support is evinced by its ultimate action in 

 clasping it. That vegetal knowledge or consciousness 

 is not animal intelligence is of course understood, but 

 that a climber's intelligence (or call it by what name 

 we choose) is higher than the equivalent of the same 



