CHEMICAL CHARACTERS OF CELL 85 



set up by the running water. At any rate it 

 falls into line with a number of so-called other 

 taxies, such as photo-taxy or the turning of 

 certain plants towards the light and so on. 



These we must look upon as examples of the 

 power of irritability which the living proto- 

 plasm is possessed of, a possession which Hert- 

 wig describes as its most remarkable peculi- 

 arity. Moreover* he says that irritability 



--, 



exhibits its specific phenomena through the 

 special structure of the irritable substance or, 

 in other words, that irritability is a funda- 

 mental property of living protoplasm, but 

 that it exhibits itself, according to its own 

 specific structure, under the influence of the 

 external world in specific energies and irrita- 

 bilities. 



The extreme school of mechanists deny that D OCS 

 there is any such thing, strictly speaking, as irritability 

 irritability and with their views as formulated exist? 

 by one of the most recent and most able writers 

 on the subject, M. Le Dantec,t it will now be 

 necessary to deal. 



Spontaneity of movement, he tells us, is not 

 an essential character of life. "If we observe 

 with no other help than what nature affords 



* Op. cit., S. 136. 



t Op. cit., p. 157. Italics in quotations from this authoi 

 are as in original. 



