14 TRANSACTIONS AND PROCEEDINGS OF THE [Sess. LXi. 



recommendations, and he also limed it, but he put on no 

 nitrogenous matter. The result was that his land grew more 

 and more fertile. He used to plough in all his leguminous 

 <jrop ; by and by he reaped it, but still the fertility of the land 

 increased. At first he followed his green manuring with a 

 crop of rye, for the land was too poor to grow other cereals, 

 but by and by he found he could grow oats and barley, and, 

 in short, after a period of twenty years, he had converted a 

 sandy waste into a rich, fertile soil containing abundance 

 ■of nitrogenous matter. He declared that the nitrogen in 

 his soil came from the air, and that the leguminous plants 

 had brought it. 



He called them nitrogen collectors, and the cereal crops 

 he called nitrogen consumers. 



This remarkable experiment soon gained notoriety, and 

 farmers and scientists came annually in numbers to see it; 

 and the impression left on their minds, when they com- 

 pared this fertile farm with the barren, sandy land adjacent 

 to it, was that leguminous plants at least must surely 

 have the faculty of making use of the free nitrogen of the 

 air. 



It had the- effect of causing a number of the scientists 

 who had charge of agricultural experiment stations to 

 institute experiments anew, to test again the old vexed 

 question. 



The first of these to arrive at satisfactory conclusions 

 were Professor Hellriegel and his coadjutor. Dr. AVilfarth. 

 They began their experimental inquiry in 1883, and three 

 years later, in 188G, Hellriegel communicated to the 

 Asricultural Section of the German Naturalists, at their 

 meeting in Berlin, the interesting information that he had 

 succeeded in proving that the leguminosic were able to 

 assimilate the free nitrogen of the air, and what added 

 immensely to the interest of tliat fact was the curious way 

 in which they did it. 



I am not aware that the subject of Hellriegel's discovery 

 has ever been formally brought before the notice of the 

 Society, although most of the fellows present are doubtless 

 well acquainted with it ; jjut as it is what is called an 

 epoch inaking discovery, 1 tliink a sliort description of it, 

 even at this late date, would be welcome to some of you. 



