2BS tiow cnops T'EBr*. 



Do the Orj?anic illatters of the Soil Directly Nourish 



Vegetation? — This is a question wliifh, so far as liumns is 

 concerned, has been discussed witli g-vcat earnestness by 

 the most prominent writers on Agricultural Science. 



De Saussure, Derzelius, a:id Mulder, have argued in the 

 affirmative ; while Liebig and his numerous adherents to- 

 tally deny to humus the possession of any nutritive value. 

 It is probable that luimus may be directly absorbed by, 

 and feed, plants. It is certain, also, that it docs not con- 

 tribute largely to the sustenance of agricultural crops. 



To ascertain the real extent to which humus is taken up 

 by plants, or even to demonstrate that it is taken up by 

 them, is, perhaps, impossible from the data now in our 

 possession. AYe shnll consider the probabilities. 



There have not been wanting attempts to ascertain ex- 

 perimentallv whether hunuis is capable of feeding vegeta- 

 tion. Hartig, De Saussure, Wiegmann aiid Polstorf, and 

 Soubeiran, l;avc observed the growth of plants whose 

 roots were immersed in solutions of humus. The experi- 

 ments of Hartig led this observer to conclude that humate 

 of potash and water-extract of peat do not enter the roets 

 of plants. Kot having had access to the original account 

 of this investigation, the writer cannot, perhaps, judge 

 properly of its merits. It appears, however, that tlie 

 roots of the plants operated with were not kept constantly 

 moist, and their extremities were decomposed by too great 

 concentration of the liquid in wiiich they were immersed. 

 Under such conditions accurate results were out of the 

 question. 



De Saussure {A/ui. Ch. n. Fh., 42, 275) made two ex- 

 periments, one with a bean, the other with Polygonum 

 Persicarid, in whicli these ]ilants were made to vegetetc 

 with their roots immersed in a solution of humate of pot- 

 ash (prepared by boiHng humus with bicarbonate of pot- 

 ash). In the first case tlie bean plant, originally M'eigliing 

 11 grams, gained during 14 days 6 grms., while the 



