2 " INTRODUCTION [CH. 



The'so-icalled movements' t)F' plants are almost always due to the 

 growth of new parts and are not to be compared with the movements 

 of animals which are the result of the alteration of relative position of 

 fully formed organs. 



Another fundamental difference between animals and plants is to 

 Distinction be found in the nature of their food. Animals can 

 animals and on ^ ^ ve on com pl ex substances, not very different 

 plants. i n chemical composition from their own bodies, and 



further, they can live on solid food. Plants, on the other hand, build 

 themselves up out of carbon dioxide and other gases and out of water 

 with a few simple salts in solution, and they only take in fluids or 

 gases. There are, however, a certain number of living beings of 

 extremely low and primitive character which combine the characters 

 of animals and plants, and the question in which division they should 

 be ranked is a matter to be determined only after a study of the 

 special circumstances of each case. 



It has been pointed out that our own existence is the original 

 type from which the idea of life is derived. But we know ourselves 

 primarily not as bodies in which growth and reproduction occur, but 

 rather as conscious, thinking beings, and we are naturally inclined 

 to imagine that animals at least, which not only grow and multiply, 

 but in many other respects also resemble us, are likewise conscious. 

 How far this belief is well-founded is open to serious question, if by 

 consciousness we mean anything at all resembling our own inner life 

 the only consciousness we know anything about. The movements 

 of the higher animals suggest that they experience the feelings of 

 fear, anger, desire, etc., and it would be foolish to deny all similarity 

 between them and man in these respects, but the habit which many 

 people have of uncritically attributing purely human feelings to dogs, 

 cats, horses, etc., is apt to lead us into serious error. Our fore- 

 fathers went further than even we are inclined to do and supposed 

 all natural objects, the sun, wind, trees, etc., to have spirits, that is, 

 to be conscious. Since we can never learn much about the conscious- 

 .ness of beings with whom we cannot speak, zoologists content them- 

 selves with looking at animals entirely from the outside, without 

 enquiring as to whether or no they are conscious 1 ; animals are for 



vast bulk of normal cases which gave rise to the idea. The reasons for classify- 

 ing abnormal cases in one category or another are not general but special, and 

 have to be considered in each case. 



1 The science of Comparative Psychology endeavours to make deductions 

 about the minds of animals from their actions. 



