CHAP. XI.] THE PSYCHOLOGY OF THE GAT. 387 



This question cannot be duly considered without recognizing that 

 though living creatures have principles of individuation of the most 

 varied kinds, yet that they are susceptible of being classed in two 

 groups — animals and plants. 



As we descend to the lowest animals, the evidence as to senti- 

 ence diminishes ; while (from the resemblances of the lowest 

 animals and plants, and from the similarity of the vegetative 

 functions in all living creatures) we may analogically conclude that 

 activities take place in plants which are parallel with, and analogous 

 to the unfclt and non-neural psychoses of animals. As Asa Gray 

 has said with respect to their movements : " Although these are 

 incited by physical agents (just as analogous kinds of movements 

 are in animals), and cannot be the result of anything like volition, 

 yet nearly all of them are inexplicable on mechanical principles. 

 Some of them at least are spontaneous motions of the plant or 

 organism itself, due to some inherent power which is merely put in 

 action by light, attraction, or other external influences." 



Reference has already been made to insectivorous plants, such as 

 Dioncea. In such plants we have susceptibilities strangely like those 

 of animals. An impression is made, and appropriate resulting 

 actions ensue. Moreover, these actions do not take place without 

 the occurrence of electrical changes similar to those which occur in 

 muscular contraction. 



Nevertheless, nothing in the shape of vegetable nervous or mus- 

 cular tissue has been detected, and as structure and function neces- 

 sarily vary together, it is impossible to attribute sensations, sense- 

 perceptions, instincts, or voluntary motions to plants, though the 

 principle of individuation in each plant acts (in its degree) as do 

 the unfelt psychoses of animals, and harmonises its various vital 

 processes. 



The conception then which commended itself to the clear (and 

 certainly unbiassed) Greek intellect of more than 2000 years ago, 

 that there are three orders of internal organic forces, or principles 

 of individuation, namely, the rational, the animal, and the vegetal, 

 appears to be justified by the light of the science of our own day. 



We have no grounds for believing in the potential existence of 

 sensation in plants, inasmuch as in the highest plants it is not made 

 manifest, and no traces of sense organs have anywhere been found 

 in them. Man apart — there are two orders of internal organic 

 forces or principles of individuation — there is the animal, there is 

 the vegetal, soul or psyche. 



Now we have seen that the cat begins its existence as a minute 

 spheroidal mass of protoplasm, which is capable of spontaneous 

 di\asion and which can imbibe nutriment and grow. It is comparable 

 with a lowly organized plant. As function varies with structure 

 we cannot deny a vegetal psyche to the creature at this stage of its 

 existence, though we have no grounds for attributing to it as yet a 

 reaUy animal nature. But growth continues and produces a com- 

 plexity of structure which demands a principle of individuation of a 



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