2. INSTINCT 



We know from our last studies that the elemental 

 processes concerned in animal movements are not only 

 nervous conduction, but may also consist in facts of different 

 kinds which have forced modern authors to make use 

 again of the old word " centre " in a purely physiological 

 sense, after the anatomical meaning of this word had 

 proved to be of rather dubious value for physiological 

 analysis. It is to von Uexkuell that the most thorough 

 analysis of organic movements into their simple components 

 is due, and, in order to express the true logical value 

 of such an analysis, we did not hesitate to compare its 

 results with those furnished us by the analysis of the 

 genesis of form. 



But this comparison now has another and very im- 

 portant consequence. "We saw that form evidently was the 

 result of the arrangement of certain elements, and that 

 all genesis of form could be reduced to the constellation 

 of certain factors concerned in it ; but neither was form 

 a mere sum of those elements nor was its origin the result 

 of a mere sum of these factors. Nothing at all is proved 

 about a totality being a mere sum or not a mere sum 

 by demonstrating the elements it consists of: this holds 

 for form as well as for movements. 



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