Instincts 313 



characters present themselves exactly in the order of 

 their phylogenetic acquisition. 



If the capacity which centroepigenesis possesses of 

 explaining the Lamarckian principle extends so far as to 

 account, without needing any subordinate hypothesis, for 

 the inheritance of those characters also which either sex 

 has acquired separately and at different times and each 

 on its own account, it shows itself still more especially 

 and completely adapted to explaining the inheritance of 

 those characters common to both sexes as well as those 

 belonging only to one sex which, in consequence of their 

 excessive complexity and of the circumstance that they 

 are located not simply in definite parts of the organism 

 but rather in numberless places at the same time, have 

 so far always constituted the greatest difficulty for every 

 theory which has attempted to explain the inheritance 

 of them. We refer to the instincts. 



It is evident in fact that we can regard every instinct 

 as due to a special relative mode of being of the different 

 psychic centers and of the nervous network connecting 

 them. For it depends upon this relative mode of being 

 that to certain definite sensations which arrive at certain 

 perceptive centers there correspond necessarily certain 

 reflex movements induced by the motor centers which 

 are in definite communication with these perceptive 

 centers. Now, however, every deposition of new psychic 

 centers, perceptive or motor, mnemonic or volitional, 

 and every new connection of these by means of nervous 

 communications more or less direct or indirect, more 

 or less conductive or resistant, would be, according to 

 the centroepigenetic hypothesis, only the effect of as 

 many special modes of being of nervous circulation in 

 the limited territory of the nervous system alone. It 



