January 2, 1903.J 



SCIENCE. 



17 



this increase was necessarily the free nitro- 

 gen of the air. His objection to Boussin- 

 gault's conclusions was based upon the 

 claim that, in the confined space in which 

 the plants were forced to grow, their nat- 

 ural development was hindered. 



Ville's criticism led Boussingault to 

 repeat his experiments. In order to 

 meet the former's objection to the limited 

 amount of air in which the plants were 

 forced to vegetate, he substituted a three- 

 necked globe for the one employed before. 

 By using an aspirator the air in this globe 

 could be continually renewed, after pass- 

 ing it through a series of Wolf's bottles 

 with the proper solutions to free it from 

 nitrogen compounds. The results of this 

 second series of experiments fully corrobo- 

 rated his former conclusions. 



A committee appointed by the French 

 Academy of Sciences to investigate the 

 methods employed by Boussingault and 

 Ville held that, in the latter 's experiments, 

 the introduction of nitrogen compounds 

 was not excluded, and, therefore, pro- 

 nounced in favor of Boussingault. If any 

 doubt had remained in regard to the cor- 

 rectness of Boussingault 's conclusions it 

 was dispelled a few years later by the 

 labors of Laws, Gilbert and Pugh. These 

 investigators repeated the experiments of 

 Boussingault with expensive and improved 

 apparatus. Their work was performed 

 with the greatest care and nicety, and their 

 results fully vindicated Boussingault in 

 the position he had taken. 



The experimental evidence thus pro- 

 duced in favor of the proposition that the 

 free nitrogen of the air was not available 

 for vegetable growth was so clear and con- 

 vincing that it was readily accepted by all, 

 with the exception of one man. This man 

 was George Ville, of France. 



During all the time in which this opinion 

 prevailed, he alone remained firm in the 



belief that his observations were true, and 

 that plants could assimilate free nitrogen. 



That plants can not assimilate free nitro- 

 gen directly was established by those early 

 investigators without a doubt. On the 

 other hand, it is now equally well estab- 

 lished that free nitrogen does become avail- 

 able as plant food and plays an important 

 part in vegetable production. 



Evidently, therefore, the early investi- 

 gations must have been incomplete, and at 

 this distant day it is not difficult to point 

 out wherein they were defective. Bous- 

 singault and Ville, as well as Laws, Gilbert 

 and Pugh, regarded the soil as a mixture 

 of mineral matter and humus. They had 

 no conception of the fact that it was the 

 home of a world of living microorganisms, 

 which in a variety of ways are silently and 

 incessantly active in the transformation of 

 matter essential to vegetable growth. 

 Hence it is but natural that, in preparation 

 of soil free from nitrogen compounds of 

 all kinds, they should, what any chemist 

 under like conditions would do, subject 

 their soil to an intense heat. 



Notwithstanding the prominence of 

 these investigators and the general recog- 

 nition accorded to their conclusions, fur- 

 ther work in this connection was at most 

 only retarded but not entirely abandoned. 

 Facts known at that time, and new ob- 

 servations gradually made in studying the 

 soil in all of its phases, began to point in 

 the opposite direction. 



With the discovery of Berthelot, that the 

 fixation of free nitrogen took place through 

 the instrumentality of silent electrical dis- 

 charges in the soil, were associated the 

 manifold effects upon matter, shown to be 

 due to the action of bacterial life. These 

 latter discoveries may be divided into two 

 groups : 



1. Those showing the independent action 

 of bacteria in the soil in causing f ermenta- 



