ORGANIC MOVEMENTS 45 



an entelechian natural factor was found to be at work 

 in instinctive life, as far as the reception of stimuli is 

 concerned. 



. THE PROBLEM OF THE REGULABILITY OF INSTINCTS 



Our mention of the old physiologists may serve us as a 

 steppiog-stone to the analysis of the second chief problem 

 which instincts offer to theoretical biology. Here also the 

 main point must remain problematic, as facts are too scanty 

 at present for a definite statement. But here also the 

 analysis of possibilities may serve to give an impulse to 

 future research. 



The old physiologists, such as Treviranus and Johannes 

 Mtiller, often compared morphogenesis with instinctive life, 

 and it is to Schopenhauer that the most thorough comparison 

 between the phenomena of instinctive movements and em- 

 bryological processes is due. Instincts are regarded by this 

 school as being in some way the continuation of morphogenesis, 

 as growing upon the same ground, as governed by the 

 same reason, viz. the vital principle. 



As we have said already, we do not know at present 

 whether such a view is fully legitimate or not ; further 

 investigation will determine that. But we can make use of 

 the comparison between morphogenesis and instinct to raise 

 another question, besides the problem of the nature of the 

 instinctive stimuli, the answer to which may one day enable 

 us either to admit the autonomic nature of instincts or to 

 deny it. 



Certainly instincts are comparable with morphogenetic 

 phenomena for the simple and descriptive reason that they 



