io6 THE PSYCHIC LIFE 



The sexual elements, and especially the spermatozoid, 

 of all unicellular organisms are certainly the ones which 

 show the most highly developed psychical functions: 

 the act of seeking and approaching the ovule, which 

 is frequently situated at quite some distance from 

 where the male element is deposited; the length of 

 road to be traveled; the obstacles to be overcome; 

 all point to faculties in the spermatozoid that are not 

 explainable by simple irritability. 



Hitherto, apparently, writers who have essayed to 

 present the psychology of micro-organisms, have con- 

 tented themselves with schematic notions instead of 

 basing their theories upon the direct observation of 

 these interesting creatures. By the aid of exact data, 

 we have shown that in both vegetable and animal 

 micro-organisms phenomena are encountered which 

 pertain to a highly complex psychology, and which 

 appear quite out of proportion to the minute mass 

 that serves them as a substratum. 



We shall first of all advert to the term irritability, 

 which, though long in use, has not in our opinion been 

 happily chosen; since it is in the highest degree ambig- 

 uous, and not suggestive of an exact signification. 

 We might call to mind in this connection, the reflec- 

 tion made by Kant upon obscure properties, which he 

 compares to easj'-chairs upon which the mind unbends 

 itself and rests. In place of discussing words, let us 

 endeavor to discuss facts. 



What are we to understand by irritability ? We 

 may give the expression a very broad or a very re- 

 stricted meaning. We may make it express the prop- 

 erty which every organism possesses, of reacting 

 upon excitation. In this general sense we may say 

 that irritability includes within itself all of psychology. 



