THE ORGANIC MATTER OF THE SOIL 



135 



Monohydroxy stearic acid, 



C18H36U3 

 Agroceric acid, C21H42O3 

 Agrosteral, C22H22O . H 2 

 Paraffinic acid, C24H48O2 

 Lignoceric acid, C24H48O2 

 Phytosterol, C 26 H 4 40 . H 2 

 Pentosan, C5H3O4 

 Oxalic acid, C2H2O4 

 Succinic acid, C4H 6 4 

 Sacharaic acid, CeHsOio 

 Acrylic acid, C 3 H 4 2 

 Mannite, C 6 Hi 4 06 

 Rhamnose, CeHsOio 

 Salicylic aldehyde, 



C 6 H 4 OHCOH 



Arginine, C6H14O2X4 

 Cytosine, C4H 5 OX 3 . H 2 

 Xanthine, C 5 H 4 02X T 4 

 Hypoxan thine, C5H4ON4 

 Tysine, C6H 14 2 N2 

 Adenine, C 5 H 5 N 5 

 Choline, C 5 H 15 2 N 

 Trimethylamine, C 3 H 9 N 

 Quanine, CH 5 N 3 

 Creatinine, C 4 H 7 ON 3 

 Creatine, C 4 H 9 2 X 3 

 Nucleic acid (constitution 



unknown) 

 Trithiobenzaldehyde, 

 (C 6 H 6 CSH) 3 



From a chemical standpoint these compounds may be 

 classified under four heads : (1) those containing carbon 

 and hydrogen; (2) those containing carbon, hydrogen, 

 and oxygen ; (3) those containing carbon, hydrogen, and 

 nitrogen, or carbon, hydrogen, oxygen, and nitrogen ; 

 (4) those containing sulfur in combination with the 

 elements listed above. With the possible presence in 

 soils of compounds containing five elements, it is of 

 little wonder that the subject is a complicated one. It 

 is evident, moreover, that the list given above is only a 

 partial one, and many other compounds of an even more 

 intricate composition will later be isolated. 



So far as the plant is concerned, the compounds may 

 be divided into three groups — those that are beneficial, 

 those that are neutral, and those that are toxic, or harm- 

 ful, in their effects. As an example of the first group, 



