EFFECT OF PLANT AND ANIMAL LIFE ^S6 



matter of the soil. In sections of the country where heavy 

 winds and hurricanes are of frequent occurrence, the efficacy 

 of trees in thus burying organic matter, and producing a more 

 complete intermingling of the soils, is by no means inconsider- 

 able.^ The influence of plants in adding carbon and incidentally 

 carbonic and other organic acids to the soils has been described 

 in previous pages. When plants die and decay upon the im- 

 mediate surface, there is left only the inorganic matter or ash 

 behind, the carbonic acid escaping into the air or being carried 

 by rains into the soil. Hence it would seem to naturally follow 

 that the soil where supporting an abundant vegetation should 

 contain a larger percentage of carbonic acid than the atmosphere 

 itself. That it does not contain, in all cases, a greater amount 

 of free carbonic acid is apparently brought out in the table from 

 the works of Boussingault and Lewy, quoted on p. 156. 



Bacteria as agents of nitrification are undoubtedly efficacious 

 in preparing nitrogeneous matter in the soils for assimilation 

 by growing plants. Their influence as decomposers of rock 

 masses was noted on p. 181. According to "Wiley,^ it is highly 

 probable that organic nitrogen in the soil, in passing into the 

 form of nitric acid, exists at some period of the process in the 

 form of ammonia. The products of nitrification are ammonia, 

 nitrous or nitric acid, carbon dioxide, and water. The ammonia 

 and nitrous acid may not appear in the soils as the final products 

 of nitrification, as the organism attacks the nitrous acid at once, 

 converting it into the nitric form. 



It may at first seem strange that man, who prides himself on 

 being the highest type in the animal kingdom, as well as the 

 only animal endowed with reasoning powers; should prove the 

 most destructive; yet such is the ease. Through prodigality, 

 due in part to thoughtlessness and in part to a wilful disregard 

 for any but immediate interests, man has, apparently from the 

 very beginning of his existence, so conducted himself with re- 

 lation to natural resources as to leave little less than ruin in 

 his path. This is true not merely with reference to his treat- 



* Some of our archseologists go so far as to assert that the stone imple- 

 ments found buried several feet below tlie surface in glacial deposits, and 

 brought forward as proving the existence of pre-glaeial man, have been 

 brought into that position by just such agencies. See Holmes, Uarly Man 

 %n Minnesota, American Geologist, April, 1893, p. 228. 



« Principles and Practice of Agricultural Analysis, p. 464. 



26 



