18 LIVING PLANTS 



Aristotle's notion, which is still too preval- 

 ent, of an ascending complexity in vital phe- 

 nomena from plants to man, should be v^hol- 

 ly abandoned. The only way of viewing or- 

 ganic nature, to secure proper interpretation, 

 is that of two diverging lines of development, 

 one through motile forms, and the other 

 through fixed forms. Each line of develop- 

 ment has worked out peculiarities of its own. 

 If the special senses of animals show wonder- 

 ful adaptations, the special senses of plants, 

 although very dissimilar, will, when better 

 known, appear quite as remarkable. 



The observation of Sachs, the learned pro- 

 fessor of Wiirzburg, and one of the most far- 

 seeing of ph3^siological botanists, is particu- 

 larly pertinent in this connection. *'We have 

 no necessity," he says, ''to refer to the physi- 

 ology of nerves in order to obtain greater 

 clearness as to the phenomena of irritability 

 in plants; it will, perhaps, on the contrary, 

 eventually result that we shall obtain from 

 the process of irritability in plants data for 

 the explanation of the physiology of nerves, 

 and this, although it is as yet a distant hope, 

 gives a special attraction to the study of the 

 irritable phenomena of plants." 



