20 TEANSACTIONS AND PROCEEDINGS OF THE [Sess. Lxi. 



on in the soil whereby nitrogenous matters are converted 

 into nitric acid; and that these processes, like most other 

 chemical processes going on in the soil, are achieved 

 through the instrumentality of living organisms. The 

 characters of some of these organisms, their life history,, 

 the work in which they are engaged, and the means by 

 which that work may be controlled in some measure, so 

 as to serve specific ends, will, I understand, be demonstrated 

 at an early meeting of the Society, and it is to form a 

 kind of introduction to that practical aspect of the subject 

 that I have asked you to listen to this short historical sketch. 



Experiments with ISTitragin. By William Somerville, 

 D.Qilc., D.Sc, Professor of Agriculture, Durham College of 

 Science. 



(Read, Thursday, Uth January 1897.) 



Those who have been following tlie various developments 

 of " the nitrogen question " during the past few years 

 would be more or less prepared for the announcement that 

 appeared in the " Deutsche Landwirtschaftliche Presse," 

 on the 8 th of April last, to the eft'ect that the bacteria, 

 which establish themselves on the roots of Papilionaceous 

 plants, and enable them to utilise the free nitrogen of the 

 air, were on sale as a commercial article by the firm of 

 Meister Lucius & Brilning's successors at Hochst am 

 Main. The work of many distinguished investigators 

 during the past decade had established the fact that the 

 Papilionaceous family of the Lcguminosu! could make use 

 of the supplies of atmospheric nitrogen in a way that was 

 impossible for other plants. This power, however, is not 

 inherent in the plants themselves, but is due to colonies 

 of bacteria, which find a habitation in the wart-like nodules 

 that are normally present in abundance on their roots. 

 Without these bacteria the plants in question are in no 

 better a position than others, and although our clover, 

 peas, vetches, etc., may usually be trusted to find in the 

 soil a sullicient number of the particular bacteria that 

 they consort with, still there is always the chance that 



