DECAY CONSTANT DURING LIFE. 83 



for their replacement by ordinary acts of growth ; and that 

 even when the body has been so severely injured that the 

 organic functions are seriously disturbed for a time (as 

 when a Hydra is divided into two or more pieces, 122), 

 the vitality of the individual parts is sufficiently enduring, 

 and their reparative powers sufficiently energetic, to enable 

 them to reproduce all that is wanting for the completion of 

 the organism, and for the renewal of its ordinary actions. 

 Among the higher animals, the death of the organism at 

 large may be said to take place when the circulation finally 

 ceases ; since, as we have just seen, every individual part 

 must ere long lose its peculiar functional activity, and the 

 entire body be subject to decay. 



68. Prom what has been stated, it will be seen that Life 

 cannot be regarded as a condition in which decay is resisted ; 

 for an incessant decay is taking place in every living organism 

 as a necessary condition of its vital activity, being only 

 checked when that activity is itself suspended. But it is a 

 condition in which, by the wonderful harmony and mutual 

 adaptation of the operations of the different parts, the repa- 

 rative action of the Organic Functions is made to countervail 

 the destructive action involved in the exercise of the Animal 

 Faculties ; whilst the latter, in their turn, serve to furnish 

 the conditions requisite for the maintenance of the former. 

 So long as all these actions go on with regularity and com- 

 pleteness, so long the whole body lives ; but if any one of the 

 more important among them be interrupted, the stoppage of the 

 whole is the result. This relation of mutual dependence is most 

 intimate in the higher animals ; in which, by the differentia- 

 tion of the several tissues and organs, and the specialization 

 of their functions, the division of labour is carried to its 

 greatest extent, so that no part can entirely fulfil the duty of 

 any other. On the other hand, it is among those lowest 

 forms of animal life, in which there is the greatest multipli- 

 cation of similar parts, and the greatest diffusion of the same 

 endowments amongst them all, that we find the dependence 

 of the several parts of the organism upon each other to be 

 the slightest, and severe injuries to be tolerated with the 

 least general disturbance. 



