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the chemical products formed by the action of the bacteria, pro- 

 tozoa, and fungi on each other, and on the organic matter, both 

 animal and plant, that finds its way to the soil. The present method 

 is to study the soil with its complex mixture of organic and in- 

 organic compounds, and by the application of recognized methods 

 of chemical investigation unravel the mysteries tied up in it; 

 but unless we have the climatic and cultural conditions uniform, 

 we cannot hope to secure results that will be of general application. 



There have been two methods of attacking the problem: first, 

 the isolation and study of the individual organic compounds ex- 

 isting in the soil, and, second, a study of the hydrolysis products. 

 It is evident that these methods are slow and tedious and unsatis- 

 factory, but on the other hand a study of all the possible combina- 

 tions of the organic substances existing in the soil appears to be 

 an endless task in the light of our present knowledge. In brief, 

 a complete and thorough knowledge of the organic matter of the 

 soil appears possible only after we have mastered all of the bio- 

 chemical processes which are characteristic of the fungi, protozoa, 

 and bacteria of the soil, and have a much deeper insight into 

 the chemical constitution of vegetable cells than we have at the 

 present time. Our present knowledge leads us to believe that 

 it is possible to isolate an almost infinite variety of chemical 

 compounds from a soil, the number and variety reaching a limit 

 only when we have isolated all of the compounds which are pres- 

 ent in the plants which grew upon the soil, plus those compounds 

 contained in the bodies of bacteria, protozoa, and fungi, plus all of 

 the compounds which may be derived from these compounds 

 under the peculiar soil conditions of decay, oxidation, bacterial ac- 

 tion, and the secretions of fungi and living plant roots. 



