CHAPTER IX 



THE PLANT AND THE ANIMAL 



In the previous chapters we have studied three functions 

 of a vegetable organism, nutrition, growth, and repro- 

 duction, which, from a certain point of view, may be re- 

 garded as a particular case of growth. On glancing at 

 Nature superficially, and regarding only such forms and 

 phenomena as we meet at every step, we might easily 

 come to the conclusion that all the vital activities of the 

 plant are summed up in these three functions. This 

 idea has found expression more or less from time imme- 

 morial in some such definition of vegetable life as that 

 plants live {i.e. feed) but are deprived of motion, with the 

 occasional addition of voluntary motion. This absence 

 of motion and outward activity is looked upon as the 

 essential point of difl^erence between plants and animals ; 

 and vice versa, this is why a man, whose life is spent 

 lazily, in little more than eating and sleeping, is said 

 to be vegetating. But is such a general statement 

 about the plant justifiable ? A broader outlook upon 

 the vegetable kingdom and a closer study of the plant 

 will soon prove how hasty such an opinion is. We find 

 with amazement that, far from being absent, the pheno- 

 mena of motion are even widely spread in the vegetable 

 world. 



Let us turn first of all to the microscope and 

 study with its help a fully - developed uninjured cell 

 under the most natural conditions possible. We 

 choose for this purpose hairs found on the surface of 

 stems and leaves or of young roots, and consisting either 

 of a single cell or of a single row of cells ; or we may make 



