16 



SCIENCE. 



[N. S. Vol. XVII. No. 4ia 



ago Buchner startled the scientific world 

 by the announcement that he had produced 

 alcoholic fermentation without the pres- 

 ence of a single living germ. By simply 

 mixing the extract, obtained by strong 

 pressure from brewer's yeast, containing 

 nothing but dead organic matter, he caused 

 a solution of grape sugar to ferment, and, 

 in fact, much more rapidly than if the 

 yeast itself had been employed. Not only 

 this— Buchner showed, furthermore, that 

 the activity of this extract was com- 

 pletely destroyed at a temperature below 

 that required to kill the yeast plant. This 

 is the important point in Buchner 's obser- 

 vations, because it was the failure to recog- 

 nize this fact by Pasteur and his adherents 

 that helped, more than anything else, to 

 give the death blow to Liebig's theory. 

 It is true that Liebig at first did not regard 

 his pi;trescible matter or ferments as a 

 product of the ever-present organisms, and 

 it is also true that in Buchner 's extract it 

 is the enzyme of the yeast plant which 

 produces the molecular disturbance that 

 causes the grape sugar to break up into 

 alcohol and carbon dioxide ; yet it is grati- 

 fying to all those who were students of the 

 great master to learn that, in the main, 

 his attitude toward the process of fermen- 

 tation has been finally vindicated. 

 . It was the desire of the writer to discuss 

 on this occasion some subject related to 

 that branch of chemistry with which he is 

 at present identified, and for this purpose 

 the investigations in regard to assimilation 

 of free nitrogen by plants were selected for 

 consideration, since this question belongs 

 in the category of 'incomplete observa- 

 tions. ' 



The importance to agriculture of know- 

 ing whether plants were capable of assimi- 

 lating the free nitrogen of the air was 

 impressed upon the minds of the early 

 investigators of the subject of plant nutri- 



tion, because if this element in the free 

 state so liberally supplied by nature should 

 be found to be available as plant food, then 

 it would fall into the same class with car- 

 bon, hydrogen and oxygen, which furnish 

 the bulk of all vegetable matter, and about 

 whose source the farmer need have no con- 

 cern. In the early fifties the French 

 chemist, Boussingault, conducted his mem- 

 orable experiments with various kinds of 

 plants in order to settle this question. His 

 apparatus consisted of a large glass, one- 

 necked globe, into which he introduced a 

 sufficient quantity of soil freed from nitro- 

 gen compounds by ignition. In this soil 

 he planted a certain number of seeds, sup- 

 plied a sufficient amount of water and then 

 hermetically sealed into the neck of the 

 globe a smaller one SRed with carbon di- 

 oxide. Under this arrangement the seeds 

 were allowed to germinate and the plants 

 to grow. After a period of several weeks 

 the plants with their roots were carefully 

 removed, dried, weighed and the nitrogen 

 determined. He then determined the ni- 

 trogen in a like number of seeds themselves 

 and compared the results. Out of four- 

 teen experiments with various kinds of 

 plants, including the legumes, he found in 

 eleven cases a minus quantity of nitrogen 

 in the plants and in the other three a small 

 plus quantity. The latter results, how- 

 ever, he considered within the limits of 

 errors of observation. His conclusion, 

 therefore, was that the free nitrogen was 

 not available plant food. 



At the same time another French chem- 

 ist, Ville, investigated this problem. His ex- 

 periments were made on a somewhat larger 

 scale, his apparatus consisting of iron sash 

 filled with glass. Ville uniformly found 

 a marked increase in the content of nitro- 

 gen of the plants over that of the seeds, 

 and since nitrogen compounds had been 

 excluded during the time of his experi- 

 ments, he concluded that the source of 



