16 



10. Amines 



Trimethylamine, (CH 3 ) 3 N. Shorey (1913) 



Choline, HON(CH 3 ) 3 -CH 2 -CH 2 OH. Trimethyl oxyethyl am- 

 monium hydroxide. Shorey (1913) 



Creatinine, C^NaO. ^,-imino (n) methyl a -keto tetrahydro gly- 

 oxalin. Shorey (1911), Schreiner, Shorey, Sullivan and Skinner 

 (1911) 



11. Organic phosphorus compounds 



Nucleic acid. Shorey (1911 a, 1912, and 1913) 

 Lecithin, Aso (1904), Stoklasa (1911). 



12. Amino acids 



Arginine, CoHu&Os. a -amino, g-guanidine valerianic acid. 



Schreiner and Shorey (1910 a, 1910 d) 

 Histidine, GiH fl N 3 O 2 . a -amino, #-imidazole propionic acid. 



Schreiner and Shorey (1910 a, 1910 d) 

 Lysine, CeHnN 3 O2. a -di-amino, caproic acid. Shorey (1913) 



Whether all of these compounds have actually been isolated 

 is perhaps an open question, in view of the minute quantities which 

 were obtained, insufficient in many cases for an, exact chemical an- 

 alysis as stated by Schreiner and Lathrop (1911) : 



The amount of a substance obtained may be so small that extreme puri-' 

 fication is out of the question, and therefore) in such cases, where distinct 

 crystalline form or characteristic tests are not available the identification 

 becomes uncertain, as neither melting point nor analysis can be made. 



E. The Origin of Organic Compounds in the Soil. 



Chardet (1914) gives a discussion of the possible origin of 

 certain organic nitrogenous compounds that have been isolated 

 from the soil or might be expected to exist. 



A very complete summary of our present knowledge of the or- 

 ganic matter of the soil is presented by Jodidi (1914) under these 

 headings: I. Introduction; II. The sulphur compounds of the 

 soil; III. The influence of certain factors on the quantity of nitro- 

 gen contained in the soil ; IV. The nature of humus substances ac- 

 cording to the older authors ; V. The observations of later authors 

 concerning the nature and behavior of humus to certain reagents ; 

 VI. Genetic relationship between the chemical compounds in the 

 soil and those in plants and animals ; VII. The nature of nitrogen 

 compounds in the soil; VIII. The organic nitrogenous compounds 

 of the soil ; IX. Separation of the nitrogenous compounds in a 

 sulfuric acid extract (i. e., hydrolysate) of the soil; X. Cleavage 

 products of nucleoproteins ; XL Lecithin products in the soil; XII. 

 Pyridine derivatives in the soil ; XIII. Ammonification of amino 

 acids and acid amides in the soil ; XIV. The occurrence of hydro- 

 carbons, alcohols, and aldehydes in the soil; and XV. The organic 

 acids occurring in the soil. 



Different investigators have succeeded in isolating from soils 

 the following nitrogenous compounds which may be related to 

 or derived from the proteins: tetracarbonimid, a-picoline y-car- 

 boxylic acid, trimethylamine, nucleic acid, arginine, histidine, 

 lysine, proteoses, and peptones. Potter and Snyder (1915 b) have 

 shown that in some soils, at least, free amino acids and peptides 

 occur but the amounts are very small. 



Since there have been so many nitrogenous compounds isolat- 



