284 THE LIFE OF THE PLANT 



all living beings had to be taken into consideration 

 as a whole. Then the unity of the organic world 

 had to be admitted, and the realisation dawned that 

 all our divisions are only the production of our own 

 mind. I agree that the former conception was 

 among the greatest acquired by the human mind ; 

 it would have been quite impossible to master without 

 it the chaos of individual forms. We must not lose 

 sight, however, of the real value of the logical method 

 we are using ; we must not identify types and abstract 

 ideas with real existences. 



Granting, however, that such a dualism does not exist 

 in the organic world, that instead of considering plants 

 and animals as two absolutely different categories of 

 beings we are to realise them only as two typical concep- 

 tions, nevertheless once our mind has formed these two 

 conceptions we must do our best to describe them, 

 pointing out the peculiarities to which we give prefer- 

 ence, and which of them we connect with the conception 

 of a plant. 



I do not think we can offer to-day any shorter 

 and more appropriate definition than that expressed in 

 the old saying, that ' a plant grows, but is deprived of 

 voluntary movement.' Let us try to discover a more 

 definite meaning for this saying. The movement of an 

 animal, as indeed any kind of motion, is governed by 

 general mechanical laws. The peculiarity of the animal 

 consists in the fact that the centre of the forces acting 

 upon it lies within itself, hence its independence of 

 external conditions. The source of these forces is con- 

 cealed in the process of oxidation. This takes place all 

 over the body, manifests itself in respiration, and 

 becomes the source of the heat and motion, which, on 

 the whole, characterise the animal in contradistinction to 

 the plant. I say 'on the whole/ because we have only 

 just found ample proof that these processes are also 

 met with in plants ; but there they recede into the 



