ORGANIC CONSTITUENTS Of THE SOIL SOLUTION 95 



v. Quinic acid, which is found with quinine in the cinchona bark, 

 also occurs in beet leaves, certain hays, cranberry leaves, and occasionally 

 in other plants. 



w. Quinone has been shown to result from the action of a certain 

 fungus, Streptothrix chromogena, common in soils. 



x. Cinnamic acid is found in certain barks, and forms esters which 

 have been found in the leaves of various plants. 



y. Cumarin has been found in a large number of plants, including 

 the grasses, beets, sweet clover, etc. 



z. Daphnetin occurs in some species of Daphne and is closely related 

 to cumarin. 



aa. Esculin, as well as the corresponding esculetin, has been found 

 occasionally in a number of plants. 



bb. Heliotropine, or piperonal, has the odor of heliotrope and is found 

 in flowers. 



cc. Borneol occurs in needles of different varieties of pine, fir, spruce 

 and hemlock, golden rod and thyme. 



dd. Camphor is closely related chemically to borneol and is secreted 

 by a number of plants; it is found in the wood of Cinnamomum, cinna- 

 mon root, in the leaves of sassafras, spikenard, rosemary, rosewood, etc. 



ee. Turpentine is a constituent of many plants and coniferous trees. 



Finally, a number of organic substances has been isolated from 

 soils. Their composition, and in several cases their constitutions 

 have been determined. The effects of these on plants, when 

 they are present in the cultural media have been studied. Thus, 

 Shorey 1 was able to isolate picoline carboxylic acid (C 7 H 7 NO 2 ) 

 from certain soils in Hawaii, and this same substance has since 

 been found in several soils of the United States. In aqueous 

 solutions it is quite toxic to wheat seedlings. Since then a num- 

 ber of other definite organic compounds have been isolated from 

 soils belonging to at least eight different classes of organic sub- 

 stances, including: 2 



Hentriacontane, C 31 H 64 . 



Monohydroxystearic acid, CH 3 (CH 2 )^CHOH(CH 2 ) 9 COOH. 



Dihydroxystearic acid, CH 3 (CH 2 ) 7 CHOH.CHOH.(CH 2 ) 7 

 COOH. 



1 Organic nitrogen in Hawaiian soils, by E. C. Shorey, report of 

 Hawaii Experiment Station, 1906, 37-59. 



2 Chemical Nature of Soil Organic Matter, by Oswald Schreiner and 

 Edmund C. Shorey, Bull. 74, Bureau of Soils, U. S. Department of Agri- 

 culture, 1910. 



