ABSTRACTS OF REPORTS OF FOREIGN INVESTIOATIOXS. 



Experiments on root tubercles and the fixation of atmospheric 

 nitrogen, J. B. Lawes and J. H. G-ilbert.— [As stilted in tlu- siccouiit 

 of tlie nu'ctiiiii^- of the sectiou for a^Ticultural cliemistiy of tlie (leniian 

 Association for the advancement of science {Ahtheilunff fiir Afjriknltur- 

 ehrmie und houhmrtliHcliaftliclies Versuchstvesen dor (tc.sdl.sclKiff dciit- 

 scher J^^atur/orschcr und Acrzte) at Halle, in the Experiment Station 

 Keeord, vol. ill, p. 207, a paper was presented by I'rof. J. II. Gilbert, LL. 

 D., F. IJ. S., on the resultsof experiments at Eothamsted on the fi\ati(>n 

 of free nitrogen by plants, with special reference to the ocenrrcnce and 

 functions of root tubercles. The following- abstract of his paper has 

 been furnished by Professor Gilbert:] 



From the results of the experiments of Boussinganlt and also of 

 those made at Eothamsted under conditions of sterilization and 

 indosure more than 30 years ago, Sir J. B. Lawes and J. H. Gilbert 

 had always concluded that at any rate our agricultural plants di<l not 

 assimilate free nitrogen. They had also abundant CAidence that \\\^ 

 rapilionacea3 as well as other plants derived nnich nitrogen from the 

 combined nitrogen in the soil and subsoil. Still they had long recog- 

 ui7.e«l that the source of rtie Avhole of the nitrogen of the PajuliouacciB 

 was not explained, that there was in fact ''a missing link." They were 

 therefore prepared to recognize the importance of the results regarding 

 the root tubercles and their connection with the assimilation of nitrogen 

 by legumes,* first announced by Professcu- Ilellriegel in l.S,S(>, and they 

 had hoj)ed to commence experiments on the' subject in 1.S87, but llu'y 

 had not been able to do so until 1888. These first results show ed a 

 considerable formation of nodules on the roots, and, coincidently, great 

 gain of nitrogen in plants grown in sand (with the idantash) when it 

 was microbe-seeded with a turbid watery extract of a rich soil. 



In 1889 and since they made a more extended series of experiments. 

 The plants were gjown in pots in a glass house. Tiiere were four pots 

 of each descrii^tion of plant, one with sterilized sand and the plant 



*A brief review of the history of investigations in this line was given by Professor 

 Gilbert, but was not deemed by him essential for this abstract, which is intended 

 to present only the general plan and results of the last Kothamstcd investigations, 

 with a few typical illustrations selected from a large iinmber of exi)erinien(s. Fur 

 a review of this subject see Experiment Station Record, vol, Ii, ji. (jSO. ;md vol. iii, 

 p. 56. 



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