INTRODUCTION. 11 



is accompanied by fire, contrast with the detonating combi- 

 nation of chlorine and hydrogen, which explodes when the 

 sun's rays fall directly upon it (more especially the violet 

 rays). Metamorphosis, union, and separation afford evi- 

 dence of the eternal circulation of the elements in inorganic 

 nature no less than in the living cells of plants and animals. 

 "The quantity of existing matter remains, however, the 

 same ; the elements alone change their relative positions to 

 one another." 



We thus find a verification of the ancient axiom of Anax- 

 agoras, that created things neither increase nor decrease in 

 the Universe, and that that which the Greeks termed the 

 destruction of matter was a mere separation of parts. Our 

 earthly sphere, within which is comprised all that portion 

 of the organic physical world which is accessible to our ob- 

 servation, is apparently a laboratory of death and decay ; but 

 that great natural process of slow combustion, which we call 

 decay, does not terminate in annihilation. The liberated 

 bodies combine to form other structures, and through the 

 agency of the active forces which are incorporated in them 

 a new life germinates from the bosom of the earth. 



