THE PLANT AND THE ANIMAL 117 



partaking of both it may be infinitesimally, is a reaction 

 simply undecided, and therefore vaguely conscious. 

 This amounts to saying that the humblest organism 

 is conscious in proportion 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 locomotion. 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 dis 

 appearance 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 con 

 jecture that consciousness is even weaker in animals of 

 this kind than in organisms much less differentiated, 

 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 direction 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. 

 &quot; Unconscious &quot; and &quot; conscious &quot; are not two labels 

 which can be mechanically fastened, the one on every 

 vegetable cell, the other on all animals. While conscious- 



1 Cope, op. cit. p. 76. 



