142 THE BEGINNINGS OF LIFE. 



vanquished by this effort, and, as it were, broken, it 

 returns as crude matter to the source whence it had 

 come/ c Thus,' Dumas also says, c is the mysterious 

 circle of organic life upon the surface of the globe 

 completed and maintained! The air contains or en- 

 genders the oxidized substances required carbonic 

 acid, water, nitric acid, and ammonia. Vegetables, true 

 reducing apparatus, seize upon the radicals of these, 

 carbon, hydrogen, azote, ammonium; and with them 

 they fashion all the variety of organic or organizable 

 matters which they supply to animals. Animals, again, 

 true apparatuses of combustion, reproduce from them 

 carbonic acid, water, oxide of ammonium, and azotic 

 or nitric acid, which return to the air to reproduce the 

 same phenomena to the end of time.' 



Thus we see that throughout vast epochs, and even 

 in the present day, the Vegetable Kingdom has been, 

 and now constitutes, the great laboratory in which the 

 combination of dead inorganic or mineral materials into 

 living matter is continually taking place. We have 

 also seen that animals have no such direct power of 

 elevating matter taken immediately from its inorganic 

 sources, that they, on the contrary, avail themselves of 

 the previously constructive energies of plants, and use 

 for the building up of their own tissues complex sub- 

 stances which have been obtained, more or less directly, 

 from the members of the vegetable kingdom. We have 

 next to enquire briefly into what has been called the 

 c Theory of Organization/ in order to learn how far 



