FIRST REPLY. 149 



dred years longer. Such a store corresponds to about 

 12,025,000,000 tons of carbon, which these plants evi- 

 dently could not have acquired from the soil of the ancient 

 world, in which no humus existed. That unsound argu- 

 ment does, in fact, silently pre-suppose the following 

 hypothesis : 



" There exists on the earth a definite quantity of organic 

 matter, which circulates between the vegetable and animal 

 kingdoms; the decaying animal serves as nutriment to 

 the plant, and the developed plant again to the animal." 



Now this might certainly be the case if the putrefactive 

 process did not come between, through which undoubtedly 

 at least a portion of the organic matter is continually being 

 withdrawn from the pretended circle, and dissipated in the 

 atmosphere in the shape of inorganic compounds, carbonic 

 acid and ammonia. In the course of thousands of years, 

 the organic substance, which it is thus assumed was at 

 once created with the earth, must have long since been 

 used up. But we find exactly the contrary. Equally in 

 the course of the great geognostic periods, and in the course 

 of the history of the earth beginning with mankind, there 

 is seen, in the former from period to period, in the latter 

 from century to century, an ever-increasing fulness of 

 organic life, an incessant multiplication in the animal and 

 in the vegetable world. Whence springs this, if there is 

 no process by which the inorganic matter is carried over 

 into the circle of the organic ? On the other hand, we 

 may easily imagine what enormous quantities of ammonia 

 and carbonic acid must have been poured forth into the air 

 during the thousands of years, by respiration and combus- 

 tion, from the decomposition of so many thousand millions 

 of animal and vegetable bodies, and by the continual flow 

 from the great volcanoes ; while the fact is, that ammonia 



