28o THE LIFE OF THE PLANT 



life. Failing to find in the surrounding medium the 

 necessary conditions for life, it reacts on itself, and 

 during this internal process breaks down, becomes 

 exhausted, and dies. But the moment we remove it 

 from the suffocating atmosphere, and by taking off the 

 glass bell give the organism the chance of breathing 

 freely, fermentation stops at once ; the pathological 

 process of fermentation is replaced by the physiological 

 process of respiration, the work of destruction is replaced 

 by that of construction ; healthy and normal life asserts 

 its rights, and motion and development follow as fellow 

 travellers. Hence respiration conditions the very exist- 

 ence of organisms, be they animals or plants. 



Much has already been said about the impossibility of 

 establishing any difference between the two kingdoms, 

 on the ground of the presence or absence of movement. 

 One more question remains to be discussed. Is the plant 

 capable of voluntary movement ? Before answering this 

 question we must agree as to what we mean by voluntary 

 movement, or speaking generally by a voluntary pheno- 

 menon. If the term implies a phenomenon produced 

 without cause science will not admit such even in the 

 sphere of animal life ; if the term implies a phenomenon 

 produced by internal, hidden causes, then voluntary 

 may also in the meantime be understood to connote 

 the movements of protoplasm, antherozoids, and the 

 leaves of Desmodium, because all these movements take 

 place without any apparent stimulus, under the influence 

 of internal forces peculiar to the organism. But if 

 capable of movement why may not a plant also feel ? 

 If we allow the response to stimulus, i.e. irritability, 

 stimulation, to be a sign of feeling we are bound to re- 

 cognise this faculty in the plant. In fact if a man is 

 pinched, tickled, or pricked without responding to these 

 stimuli, we decide that he has become insensible (be- 

 come unconscious) ; but as soon as he begins to respond 

 to them, by some movement, we say that he has regained 



