42 THE FUNCTIONS OF LIFE. 



cation of this purified material to the wants of 

 the system, to the extension of the organs, to the 

 reparation of their losses, and to the restoration 

 of their exhausted powers. 



Life, then, consists of a continued series of 

 actions and reactions, ever varying, yet con- 

 stantly tending to definite ends. Most of the 

 parts of which the body consists undergo con- 

 tinual and progressive changes in their dimen- 

 sions, figure, arrangement, and composition. 

 The materials which have been united together 

 and fashioned into the several organs, are them- 

 selves successively removed and replaced by 

 others, which again are, in their turn, discarded, 

 and new materials substituted, though without any 

 perceptible change of external form. Perpetual 

 mutation appears to constitute the fundamental 

 law of living nature ; and it has been further 

 decreed by the power which gave the first im- 

 pulse of animation to this organized fabric, that 

 its movements and its powers shall be limited in 

 their duration, and that, even when they are not 

 destroyed by extraneous causes, after continuing 

 for a certain period, they shall come to a close. 

 The law of Mortality, to which all the beings 

 that have received the gift of life are subjected, 

 is a necessary consequence of the law of muta- 

 tion; and the same causes that originally effected 

 the developement and growth of the system, and 

 maintained it in the vigour of its maturity, by 



