36 ELEMENTARY STRUCTURE OF ORGANIZED BODIES. 



the tree, the blood flows through the animal, and in both 

 there is, besides, the incessant movement of growth, decom- 

 position, and renovation. 



33. Their mode of formation is also entirely different. 

 Unorganized bodies are either simple or made up of ele- 

 ments unlike themselves ; and when a mineral is en- 

 larged, it is simply by the outward addition of particles 

 constituted like itself. Organized bodies are not formed 

 m this manner. They always, and necessarily, are derived 

 from beings similar to themselves ; and once formed, they 

 always increase interstitially, by the successive assimilation 

 of new particles, derived from various sources. 



34. Finally, organized bodies are limited in their duration. 

 Animals and plants are constantly losing some of their parts 

 by decomposition during life, which at length cease to be 

 supplied, and they die, after having lived for a longer or 

 shorter period. Inorganic bodies, on the contrary, contain 

 within themselves no principle of destruction ; and unless 

 subjected to some foreign influence, a crystal or a rock would 

 never change. The limestone and granite of our mountains 

 remain just as they were formed in ancient geological 

 epochs ; while numberless generations of plants and ani- 

 mals have lived and perished upon their surface. 



SECTION II. 



ELEMENTARY STRUCTURE OF ORGANIZED BODIES. 



35. The exercise of the functions of life, which is the 

 essential characteristic of organized bodies, (32,) requires a 

 degree of flexibility of the organs. This is secured by 

 means of a certain quantity of watery fluid, which pene- 



