THE SENSES OF PLANTS. 



519 



the pulls 8,nd strains to which they are subjected. A characteristic 

 form of some genera, as Bauhinia, is ribbon-like, but with alter- 

 nate bulgings of a cup-like form. These meet any strains acting 

 laterally, just as the cup-shaped diaphragm of the bamboo exerts a 

 pull downwards. They are, in fact, " arches " on opposite sides. 

 In the " Monkey -ladder " (Caulotretus), besides the flat stem with its 

 attendant cups. Nature has stiffened it by placing flanges at the sides, 

 thus making a girder. A Bauhinia stem, without flanges, is quite 

 flexible. Flowers, especially those constructed to secure cross- 

 pollination, abound with special adaptations to external forces ; for when 

 the insect alights on a flower, its weight has to be borne as well as 

 other forces. Salvia affords an excellent example.* 



Do Plants show Psychological Phenomena ? — The preceding facts 

 suggest the question — Can we detect anything of the more abstract 

 qualities of a sensitive nervous system in plants? Have they thought, 

 reflection, initiation of ideas, instinct, reason, and intelligence? Let 

 us consider what an engineer may have to do. Having first had it 

 described to him what is wanted to be done, he executes most of 

 the above mental qualities before he begins to construct the work — 

 say, the Thames Embankment. Does a beaver follow the same series 

 of psychological processes? He sees the water and the place where 

 his dam shall be. He cuts down trees for the purpose, putting the 

 logs in their right positions, and the dam is made. Where is the 

 difference between an engineer and the beaver? The latter is an 

 automaton, the engineer is not. The instinct to^ make a dam is heredi- 

 tary, and the beaver will try to make it elsewhere, as in the case of 

 a certain tame one. Its owner supplied it with various articles in 

 a room, and it made a " dam " in the corner. Similarly a puppy 

 brought up by hand, when first given a biscuit, tried to bury it in the 

 wooden floor in a corner of the room left uncovered. After having 

 well scratched the boards, it proceeded to ram the biscuit down with 

 its nose. It walked away quite satisfied. Eeason was non-existent 

 in the puppy, only instinct was present; so that neither animal could 

 perceive that " circumstances alter cases." 



These two instances show that it was at first reasoning (but only 

 with concrete objects, never with abstractions) that first led the ancestral 

 beaver to make a dam and a dog to bury bones; but both have now- 

 become automatic instincts. Now, plants, having no power of thought 

 or reflection, cannot consciously initiate an act of construction. Never- 

 theless, plants do initiate all sortiS of constructions of a purposeful 

 nature, a few only of which have been described above. It is Life 

 which responds to external stimuli and proceeds to build up tissues 

 and organs to meet the case, whatever it may be, whether of a plant 

 or animal. 



We cannot go farther than to recognize JAfe as the Director of the 

 lifeless, physical forces in organisms, which moves the lifeless matter 

 derived frgm food, and thereby builds up everything that is wanted, 



* See Introduction to Plant Ecology. 



