150 WHAT DOES MAN LIVE UPON? 



only occurs in exceedingly small, uncertain quantities, and 

 carbonic acid takes a definite but exceedingly small share 

 in the composition of the atmosphere. There must, there- 

 fore, exist a regular and invariable drain, by which those 

 matters are withdrawn again from the atmosphere and 

 re-embodied in the organic world. And we can demon- 

 strate this both on a large scale and on a small, in portions 

 of the world and in still smaller spheres. 



In the Pampas of South America, existed, at the period 

 of their occupation by the Spaniards, the same thirsty 

 vegetation of the steppes as at present excepting that the 

 immediate vicinity of the towns has been altered by the 

 running wild of the great Pampas Thistle and the Arti- 

 choke the same scanty population, the same quantity of 

 indigenous animals that now wander over its desert plains. 

 The Spaniards introduced the horse and neat cattle, and 

 these multiplied in incredibly short time in such profusion, 

 that Monte Video alone annually exports 300,000 ox 

 hides ; that the military expeditions of General Rosa cost 

 many hundred thousand horses, without any diminution 

 becoming observable. 



The native organic life and its quantity have, therefore, 

 since the discovery by the Spaniards, not diminished, but 

 importantly increased, and millions of pounds of carbon 

 and nitrogen, combined into organic substances, have been 

 exported in the trade in hides, without the land receiving 

 the smallest appreciable return of organic matter. Where 

 could these masses have come from, if not from the atmo- 

 sphere ? If we leave out of view all the other constituents 

 of tea, China exports more than 300,000 Ibs. of nitrogen 

 in the half per cent of theine, without receiving any con- 

 siderable return. From forests maintained in good con- 

 dition, we annually obtain about 4,000 Ibs. of dry wood 



