ii.l THE PLANT AND THE ANIMAL 111 



both it may be infinitesimally, is a reaction simply unde- 

 cided, and therefore vaguely conscious. This amounts 

 to saying that the humblest organism is conscious in pro- 

 portion to its power to move freely. Is consciousness 

 here, in relation to movement, the effect or the cause? 

 In one sense it is the cause, since it has to direct loco- 

 motion. But in another sense it is the effect, for it is 

 the motor activity that maintains it, and, once this activity 

 disappears, consciousness dies away or rather falls asleep. 

 In crustaceans such as the rhizocephala, which must 

 formerly have shown a more differentiated structure, 

 fixity and parasitism accompany the degeneration and 

 almost complete disappearance of the nervous system. 

 Since, in such a case, the progress of organization must 

 have localized all the conscious activity in nervous centres, 

 we may conjecture that consciousness is even weaker in 

 animals of this kind than in organisms much less differen- 

 tiated, which have never had nervous centres but have 

 remained mobile. 



How then could the plant, which is fixed in the earth 

 and finds its food on the spot, have developed in the di- 

 rection of conscious activity? The membrane of cellulose, 

 in which the protoplasm wraps itself up, not only prevents 

 the simplest vegetable organism from moving, but screens 

 it also, in some measure, from those outer stimuli which 

 act on the sensibility of the animal as irritants and prevent 

 it from going to sleep. 1 The plant is therefore unconscious. 

 Here again, however, we must beware of radical distinctions. 

 "Unconscious" and "conscious" are not two labels which 

 can be mechanically fastened, the one on every vegetable 

 cell, the other on all animals. While consciousness sleeps 

 in the animal which has degenerated into a motionless 

 parasite, it probably awakens in the vegetable that has 

 1 Cope, op. cit. p. 76. 



