THE NATURE OF PLEASURE AND PAIN. 683 



its help. Moreover, mechanical adaptation to the medium becomes a 

 matter of more difficulty as we ascend in the scale of beings ; and from 

 this arise many anomalies. Individuals retain tastes which were for- 

 merly favorable, but are now useless or injurious, as the passion for 

 hunting and the warlike disposition, which are, according to Mr. 

 Spencer, relics of savage instincts. Other anomalies arise in conse- 

 quence of an antagonism between the individual and the species, as 

 when the lower animals destroy themselves by division to make new 

 beings, and some of a higher grade die immediately after performing 

 the act of reproduction. Mechanical selection is likewise incompetent 

 to give an explanation of the origin of pleasure and pain, and to throw 

 light on their primitive connection with life. We believe that there 

 is a close and strong bond between these affections of life, independ- 

 ent of natural selection, which modifies and perfects the connection, 

 but does not create it, and that we can find the' reason of this connec- 

 tion by inquiring of physiology and psychology. 



Let us inquire, first, what physiology can teach us about it. In 

 previous investigations in this direction we have reasoned too much 

 from complex organisms already developed. The thing we ought to 

 learn is what, in a cell or a nerve, arouses the rudiment of pleasure or 

 of pain, to be extended ultimately to the whole of the living body. 

 The nervous elements are constantly the scene of a double chemical 

 labor ; a " negative " work of reparation, consisting in the formation 

 of very complex albuminoid compounds ; and a " positive " one of 

 expenditure, consisting in the reduction of these compounds to more 

 simple ones. In the state of repose, these two molecular labors are 

 performed simultaneously, and are nearly in equilibrium. In that case 

 we are conscious simply of a condition of vital calm and evenness, 

 with which is connected a vague feeling of rest and comfort. An ex- 

 ternal agent, a sound, a light, or a shock, comes to excite a nerve ; the 

 interruption of the equilibrium produces a movement of nervous ex- 

 penditure, and this excites a simultaneous movement of reparation 

 just as water flowing out of a siphon-tube calls up into its place water 

 which rises. These two labors are equally necessary to life, and must 

 be suitably proportioned to one another for life to subsist. Nervous 

 reparation, which accumulates force, always has for its result and 

 object exercise, which expends force. In natural selection, the animal 

 can not be satisfied with repairing his nervous system ; he must put it 

 to use, to seek food and defend himself ; he must expend, to preserve. 

 This being so, can we assume, as Leon Dumont does ( " Theorie scien- 

 tifique de la sensibilite " ), that the accumulation of force, its " storage 

 in the nerve," is the only cause of pleasure ? Every nervous action, 

 says this author, is an expenditure of force. How can expenditure, 

 which is a loss, produce pleasure, the cause of which, on the other 

 hand, is sought in augmentation of force ? This view arises from an 

 imperfect conception of the relation of the two molecular labors. The 



