66 The Chemical Statics of Organised Beings. 



hydrogen. If a steam-engine had been employed to take him 

 there, it would have burnt from 1000 to 1200 to accomplish the 

 same work. 



Thus, viewed as a machine, borrowing all its power from the 

 coal that it burns, man is an engine three or four times more 

 perfect than the most perfect steam-engine. Our engineers have, 

 therefore, still much to do; and yet these numbers are quite 

 such as to prove that there is a community of principles between 

 the living engine and the other ; for, if we allow for all the in- 

 evitable losses in steam-engines which are so carefully avoided 

 in the human machine, the identity of the principle of their 

 respective powers appears manifest and clear. 



But we have followed far enough considerations as to which 

 your own reflections are already in advance of me, and where 

 your recollections leave me nothing more to do. 



To sum up, then, we see that of the primitive atmosphere of 

 the earth three great parts have been formed : 



One which constitutes the actual atmospheric air; the second, 

 which is represented by vegetables ; the third, by animals. 



Between these three masses, continual exchanges take place : 

 matter descends from the air into plants, enters by this route 

 into animals, and returns to the air according as these make 

 use of it. 



Green vegetables constitute the great laboratory of organic 

 chemistry. It is they which, with carbon, hydrogen, azote, 

 water, and oxide of ammonium, slowly build up all the most 

 complex organic matters. 



They receive from the solar rays, under the form of heat or 

 of chemical rays, the powers necessary for this work. 



Animals assimilate or absorb the organic matters formed by 

 plants. They change them by little and little ; they destroy 

 them. In their organs, new organic substances may come into 

 existence, but they are always substances more simple, more 

 akin to the elementary state, than those which they have received. 

 By degrees these decompose the organic matters slowly created 

 by plants; they bring them back, little by little, towards the 

 state of carbonic acid, water, azote, and ammonia, a state which 

 allows them to be returned to the air. 



In burning or destroying these organic matters, animals 

 always produce heat, which, radiating from their bodies in 

 space, goes to supply the place of that which vegetables had 

 absorbed. 



Thus all that air gives to plants, plants give up to animals, 

 and animals restore to the air; an eternal circle, in which life 

 keeps in motion and manifests itself, but in which matter merely 

 changes place. 



The brute matter of air, organised by slow degrees in plants, 



