IMPULSE AND INSTINCT 



they include so much of inherited experience as enables them 

 to find directly the means for their own satisfaction. 



Thus we get back to the difficulty of finding the limit of 

 instinct towards the lower end of the animal scale. The 

 need of nourishment, in other words, the faculty of assimilation, 

 is a fundamental property of protoplasm ; upon it depends, in 

 animals provided with nerves, the feeling of the need of taking 

 nourishment, and through inherited experience the instinctive 

 practice of satisfying the need. The question has often been 

 argued, whether a new-born child seizes the mother's nipple 

 itself or must be directed to it. Without doubt the former is 

 the case : the child feels the need of nourishment, it expresses 

 it at once by means of acquired and inherited faculties by 

 crying, by means of the same faculties it makes sucking 

 motions with its mouth, as we also do in the adult condition 

 quite unconsciously, when we have a great desire for food 

 and drink and think of them motions which in many self- 

 indulgent epicures have produced a quite characteristic form 

 of mouth, with soft prominent lips, seen, e.g., in so many clerical 

 gentlemen who find the world pleasant. These movements are 

 the same which the tongue makes in tasting, they consist prin- 

 cipally in the pressing of the tongue against the hard palate. 

 The child feels with its lips the warm soft breast of the 

 mother, and then at once seizes the nipple and sucks, in 

 accordance with its acquired and inherited faculties. Every 

 one who has watched new-born animals when sucking, knows 

 these facts, and knows that the mothers do not need to guide 

 their young to suck. 



But although the necessity of nutrition is a fundamental 

 property of the protoplasm, the question arises, at what point 

 does the inception of food cease to be a mere physico-chemical 

 act and begin to depend on nervous action ? Where does the 

 feeling of hunger commence ? This feeling must be at once 

 connected with the impulse to satisfy it, although at first 



