Chap, iii The Absorption of Nitrogen 327 



carried on for many years in numerous laboratories and 

 stations for research. The development of the idea con- 

 tinued indeed to be a charge to physiologists till nearly the 

 end of the century, and led the way to research on some- 

 what similar lines that brought forth results of the highest 

 interest and importance. 



Among the workers who were attracted to the subject 

 in France were Deherain, Joulie, Schloesing, Muntz, and 

 Laurent. Of their researches attention can be called here 

 to only the most important. 



Joulie, in 1886, led opinion in the direction of the co- 

 operation of the green plant somewhat intimately with the 

 microbe. His experiments were made in the first instance 

 with buckwheat, followed by rye-grass and trefoil. These 

 he cultivated in pots, supplying them with different kinds 

 of soil, and various kinds of manure, and analysing the 

 amounts of initial nitrogen, the nitrogen supplied, and that 

 finally contained in the crop at the conclusion of the experi- 

 ment. He concluded there is a fixation of atmospheric 

 nitrogen, and that the microbes of the soil probably play 

 an important part in bringing it about, for he thought his 

 results were unfavourable to the idea of the green plants 

 having caused it. He preferred, however, to leave the 

 explanation to the future. 



Before the next contribution from French sources was 

 made, Frank, in 1886, published some results which led him 

 to the conclusion that while soils lose nitrogen in the free 

 condition as well as in the form of various compounds by 

 drainage and by cropping, there is a greater gain of the 

 gas ; while failing to explain it, he held that the fixation 

 of nitrogen from the air takes place in the soil aided by 

 some form of vegetation. 



In 1889 Tacke showed that soil containing bacteria may 

 gain as much as 25 mg. for every 100 gms. in a compara- 

 tively short time. 



