THE DEFINITION OF LIFE. 



519 



chemical forces — could not but necessarily believe 

 that the living being, having reached its full de- 

 velopment, had only thenceforth to keep itself in 

 the most stable possible equilibrium, by counter- 

 acting the destructive effect of outward agents. 

 Others among them, better informed as to the 

 phenomenon, and seeing the meaning of the in- 

 cessant change in the organism, would not admit 

 that this movement of molecular repair could 

 be produced by general natural forces, but re- 

 ferred it to a vital force. None of them per- 

 ceived that this destruction of the organism, 

 effected under the influence of general physical 

 and chemical forces, is exactly that which pro- 

 duces the constant movement of exchange, and 

 thus becomes the cause of reorganization. 



Acts of organic destruction or disorganization 

 are directly visible to us, their signs are obvious, 

 they are renewed and clearly displayed upon each 

 vital manifestation. On the contrary, acts of as- 

 similation or organization remain wholly inward, 

 and give hardly any apparent expression ; they 

 control an organic synthesis which groups to- 

 gether in a mute and hidden way the materials 

 that are afterward to be consumed in the striking 

 manifestations of life. It is a very singular truth, 

 and one most important to be understood, that 

 these two phases of the circuit of nutrition take 

 expression in ways so contrasted, organization 

 remaining latent, and disorganization impressing 

 itself on the senses by all the phenomena of life. 

 In this case, as in most others, appearances mis- 

 lead : that which we call phenomenon of life is at 

 bottom a phenomenon of organic death. 



Thus the two factors of nutrition are assimi- 

 lation and disassimilation, otherwise called or- 

 ganization and disorganization. Disassimilation 

 always attends on vital manifestation. When mo- 

 tion occurs in man or an animal, a part of the 

 active substance of the muscle is wasted and 

 burned up ; when will and sensibility are dis- 

 played, the nerves are consumed ; when thought 

 is exerted, the brain is used up, etc. Thus we 

 may say that the self-same matter is never used 

 twice for the purposes of life. When an act is 

 through with, the little portion of living matter 

 that served to produce it is gone. If the phe- 

 nomenon appears a second time, it is by borrow- 

 ing the aid of new matter. Molecular waste is 

 always proportioned to the intensity of vital man- 

 ifestations. The more actively life is displayed, 

 the deeper and more considerable is the material 

 change. The substances thrown off in the depths 

 of the organism by disassimilation are oxidized by 

 vital combustion in proportion to the energy with 



w T hich the organs have acted. These oxidations 

 or combustions produce animal warmth, occasion 

 the carbonic acid breathed out from the lungs, 

 and the different products carried off by the oth- 

 er emunctories of the system. The body wastes, 

 and suffers a consumption and loss of weight that 

 express and measure the intensity of its func- 

 tions. In brief, in all cases, physico-chemical 

 destruction is joined with functional activity, and 

 we may hold the following proposition as an 

 axiom in physiology : Every .manifestation of a 

 phenomenon in the living being is of necessity con- 

 nected with organic destruction. 



A law like this, that links the phenomenon 

 produced with the matter wasted, or, more cor- 

 rectly, with the substance transformed, is in no 

 respect special to the living world ; physical Na- 

 ture obeys the same rule. 



So, then, a living being in the fullness of its 

 functional activity does not show us the increased 

 power of some mysterious vital force ; it simply 

 exhibits the intense activity in its organism of 

 the chemical phenomena of combustion and or- 

 ganic destruction. When Cuvier paints life in 

 its bloom and beauty in the person of a young 

 woman, he errs in supposing with the vitalists 

 that physical and chemical forces or properties 

 are then subdued or sustained by vital force. 

 On the contrary, all the physical forces are set 

 free, the organism burns and consumes itself 

 more vividly, and for that very reason life glows 

 with its full splendor. 



Stahl was right in saying that physical and 

 chemical phenomena destroy the living body, and 

 lead it to death ; but the truth escaped him be- 

 cause he failed to see that the phenomena of vital 

 destruction are of themselves the stimulants and 

 forerunners of that repair of substance hidden 

 from our sight, that lurks in the depths of the 

 tissues. All the time that the phenomena of com- 

 bustion are strikingly displayed by external vital 

 manifestations, the formative process is going on 

 in the stillness of the vegetative life. It has no 

 other expression than itself, meaning that it is be- 

 trayed in no other way than by the organization 

 and renovation of the living structure. The com- 

 parison of life to a torch is very old. That meta- 

 phor is in our time changed to a truth by Lavoi- 

 sier's means. A living being is like a burning 

 torch : the body wastes, the substance of the torch 

 burns ; the first shines with a physical flame, the 

 other with a vital flame. Yet to make the com- 

 parison absolutely exact, we must imagine a phys- 

 ical torch, with the power of lasting, maintaining 

 and renewing itself, like the vital torch. Physi- 



