88 MASSACHUSETTS HORTICULTURAL SOCIETY. 



was added they grew luxuriantly. Hellriegel's inference was that 

 the cultivated soil furnished micro-organisms and that, somehow, 

 these were connected with the nodules, and that they bi'ought the 

 free nitrogen into combination and thus rendered it available to 

 the growing plants. Professor Wolff, the Nestor of German 

 agricultural chemists, was present at the meeting and cited some 

 experiments of his own which confirmed Professor Hellriegel's 

 conclusions. 



Messrs. Lawes and Gilbert have published in a late number of 

 the " Proceedings of the Royal Society " a preliminary notice of 

 an article on " Tht Present Position of the Question of the Sources 

 of Nitrogen." 



In this they summarize their present view of this question. 

 Regarding the materials which plants may obtain through their 

 roots from the soil, they say that, " upon the whole, it seems 

 probable that green-leaved plants can take up soluble complex 

 nitrogenous organic bodies . . . and that they can transform 

 them and appropriate their nitrogen." After citing some experi- 

 ments by Frank, they add : " Here, then, is a mode of accumula- 

 tion by some green-leaved plants which allies them very closely 

 to fungi themselves . . . but, inasmuch as the action is the most 

 marked in the surface layers of the soil rich in humus . . . the 

 facts so far regarded do not aid us in the explanation of the 

 acquirement of nitrogen by deep and strong-rooted leguminosae 

 from raw clay subsoils." 



Regarding the direct acquisition of atmospheric nitrogen, 

 especially free nitrogen, b}^ the plants, Messrs. Lawes and Gil- 

 bert, in the same article, after citing the experiments of Berthelot 

 and those of Hellriegel which were announced a year ago last 

 September, say: " We have important and exact facts in the 

 cases cited -and it is at any rate clear that the reason leans to this 

 explanation of the mode in which some of the higher plants derive 

 their nitrogen, involving the supposition of the intervention of 

 micro-organisms in some way. It must be admitted, on a review 

 of the conflicting results at present at command, that they do not 

 justify any confident conclusion that the compositions supposed do 

 take place in any important degree, or that free nitrogen is to any 

 important extent brought into combination under the influence of 

 the latter organisms." On the whole, they seem to doubt whether 

 tiie amount of nitrogen taken from the atmosphere by either the 



