ORGANJC MATIKKS OF THE SOIL. 237 



(such as Ink) which cannot nourish tlie plant. The latter 

 (ink, etc.) leave evidences of their entrance into the plant, 

 while the former are changed and partly assimilated. 



"A bean 15 inches high, whose roots were placed in a 

 decoction of Brazil-wood (to whicli a little alum had been 

 added and which was filtered), was able to absorb no more 

 than the fifth part of its weight of this solution without 

 wilting and dying. In this process four-fifths of its stem 

 was colored red. 



'•'•Polygomcm Persicaria (on occasion an aquatic or bog 

 plant) grew very well in the same solution and absorbed 

 its coloring matter, but the color never reached the stem. 

 The red principle of Brazil-wood being partially assimilat- 

 ed by the Polygonum, ixnderwent a chemical change; 

 while in the bean, which it was unable to nourish, it suf- 

 fered no change. The Polygonum itself became colored, 

 and withered when its roots were immersed in diluted 

 ink." 



Blot {Comptes Rendns, 1837, 1, 12) observed that the 

 re<l juice of Phytolacca decandra (poke-weed), when 

 poured upon tlie soil in which a wliite hyacinth was blos- 

 soming, was absorbed by the plant, and in one to two 

 hours dyed the flowcis of its own color. After two or 

 three days, however, the red color disappeared, the fiow- 

 ers becoming white again. 



From the facts just detailed, we conclude that some 

 kinds of organic matters may be absorbed and chemically 

 changed (certain of them assimilated) by agricultural 

 plants. 



We must therefore liold it to be extremely probable 

 that various forms of humus, viz., soluble humates, ulmates, 

 crenates, and apocrenates, together with the other soluble 

 organic matters of the soil, ai-e taken i;p by plants, and 

 decomposed or transformed, nay, we may say, assimilated 

 by them. 



