160 MENTAL EVOLUTION IN ANIMALS. 



stimulus to an action apparently instinctive, ex hypothcsi tlie 

 action could not be (according to my definition) really 

 instinctive ; and conversely, if a perception could act as a 

 stimulus to an action apparently reflex, the action could not 

 be (according to my definition) a true reflex. Therefore, if 

 we agree to limit the term Instinct to nervous processes 

 involving a mental element, it follows that this element is 

 perception, and that it is always involved in every stimulus 

 leading to instinctive action. 



With reference to general principles of classification it is 

 only needful for me further to quote the following extract 

 from my previous work : — 



" The most important point to observe in the first instance 

 is that instinct involves mental operations; for this is the 

 only point that serves to distinguish instinctive from reflex 

 action. Reflex action, as already explained, is non-mental 

 neuro-muscular adaptation to appropriate stimuli ; but in- 

 stinctive action is this and something more ; there is in it 

 the element of mind. No doubt it is often difficult, or even 

 impossible, to decide whether or not a given action implies 

 the presence of the mind-element — i.e., conscious as distin- 

 guished from unconscious adaptation ; but this is altogether 

 a separate matter, and has nothing to do with the question 

 of defining instinct in a manner which shall be formally 

 exclusive, on the one hand of reflex action, and on the other 

 of reason. As Virchow truly observes, ' it is difficult or 

 impossible to draw the line between instinctive and reflex 

 action ;' but at least the difficulty may be narrowed down to 

 deciding in particular cases whether or not an action falls 

 into this or that category of definition ; there is no reason 

 why the difficulty should arise on account of any ambiguity 

 of the definitions themselves. Therefore I endeavour to ' 

 draw as sharply as possible the line which in theory should 

 be taken to separate instinctive from reflex action ; and this 

 line, as I have already said, is constituted by the boundary 

 of non-mental or unconscious adjustment, with adjustment in 

 which there is concerned consciousness or mind." 



I shall now proceed to show, by a few selected examples, 

 what has been called the Perfection of Instinct ; next I 

 shall similarly illustrate the Imperfection of Instinct ; and 

 lastly, I shall discuss the important question of the Origin 

 and Development of Instinct. 



