FROM THE AIR BY THE LEGUMINOS^ 2$ 



tlial bacteria played an imporlanl part in liie fixation of 

 atmospheric nitrogen by the Leguminosie. 



In order to test this theory, HeUriegel used c|iiartzose 

 sand as the plant medium, and carried out a number of 

 comparative tests, using for watering purposes infusions 

 of soil prepared under certain conditions. The micro- 

 organisms being present in vast numbers in the soils taken 

 a simple solution was sure to contain some. After having 

 calcined the sand, the author filled glass vessels with 

 it and planted peas in them. Some were watered with 

 distilled water, others with a soil solution, and the 

 remainder with a soil solution which had been raised 

 to boiling point. The object of this latter operation was 

 to test the el^cacv of the soil solution, to ascertain, that is, 

 whether the bacteria would have any effect, as they are 

 unable to withstand a temperature of more than 60° to 70° C. 



The results were thoroughly conclusive, and the plants 

 watered with the soil solution continued to grow, whilst the 

 others withered as soon as the nitrogen of the seed, was 

 exhausted. 



The following tables show the results obtained, and 

 demonstrate, without a shadow of doubt, the influence of 

 bacteria on the formation of nodules and their faculty of 

 fixing atmospheric nitrogen. 



Experiments to show the Influence of a Soil Infusion on the 



Acquisition of Nitrogen. 



f ^■'■^v,"'fK"'.h Balance of 



furn.shed by the nitrogen 



aerial portion " 



2-838 ... - 0-050 



1S87 

 Without soil in- 

 fusion 



1887 



With infusion of 



sandy soil 



2-927 ... — o 049 



6*223 ... - 0*064 



6-858 ... - 0-064 



11-936 ... + 0-105 



15-324 ... + 0169 



11-037 ... + 0-042 



17-077 ... + 0-183 



16-864 ••• + 0'326 



18-190 ... + 0-373 



11-686 ... + 0-330 



16-411 ... + 0*421 



