INTRODUCTION. 



ped beyond recal the body dies. After death, the elements which 

 composed it, delivered to the ordinary chemical affinities, soon 

 separate to form other and new combinations. 



All living bodies die after a period of which the limit is de- 

 terminate for each species ; and death indeed appears to be a 

 necessary result of vital action, which insensibly alters the 

 organic structure. The living body, which derives its mys- 

 terious birth from another living body which has preceded it, 

 at first enlarges in dimensions, according to certain proportions 

 and limits fixed for each species, and for each of its parts ; these 

 parts gradually increase in density ; the fibres and vessels which 

 compose them imperceptibly acquire a rigidity which unfits them 

 for the discharge of their functions, the vital impulse ceases, 

 and the body naturally dies. In short, absorption, assimilation, 

 exhalation, developement, and generation, are functions common 

 to all living beings ; their birth and their .death the universal 

 terms of their existence. 



Organization presupposes life, and the organization of each 

 being implies the life proper to that being. Life indeed is 

 never seen but in connection with an organized body ; and all 

 the ingenuity of the materialist has failed to show, that par- 

 ticles of matter can organize themselves, or be organized by 

 any combination known in chemistry. In fact, vitality exercises 

 upon the elements which form at each instant part of the living 

 body, an action contrary to what the ordinary chemical affini- 

 ties can produce without this master agent ; and no power in 

 nature is known capable of reuniting again, in the same manner, 

 the atoms which have been disjoined by death. 



Animal life is distinguished from vegetable life by the power 

 of locomotion and sensation ; the first is active the other pas- 

 sive. The nourishment of plants is derived through the me- 

 dium of their roots ; that of animals through a central organ of 

 digestion destined to receive the food. The organization of this 

 cavity and its appurtenances varies according to the nature of the 

 aliments and the alterations which they undergo before furnish- 

 ing fluids proper to be absorbed ; while the atmosphere and the 

 earth supply vegetables with juices ready for absorption. Ani- 

 mal bodies, besides, at least those classes higher in the scale of ex- 

 istence, possess a circulating system, muscles for voluntary move- 



