1. THE MOST SIMPLE TYPES OF ORGANIC MOVEMENTS 



When I first tried, six years ago, 1 to classify organic 

 movements according to their degree of complication, it 

 seemed inevitable that the classification must start from 

 two types, which in different respects are the most simple 

 ones : the so-called simple reflex, and the simple free 

 directive motion called " taxis. " 



Modern investigations have proved that these two groups 

 of movements, though the most simple in concept, are far 

 from being the most fundamental in fact, and therefore a 

 classification of organic movements at the present day will 

 have to follow other lines of analysis. But in spite of that, 

 for historical interest, a short survey of the theory of the 

 simple reflex and of the simple directive movement may 

 introduce the present chapter. 



a. THE SIMPLE EEFLEX 



The simple reflex occurs in plants, in the Mimosa for 

 instance, as well as in animals, and in the latter both when 

 they possess a well localised brain and nervous system 

 and when they do not. Coughing and sneezing are among 

 the most universally known phenomena of this class. A 

 stimulus applied to a specified point of the body is followed 



1 Die "Seele" als elcmentarer NaturfaJctor, Leipzig, 1903. 



8 



