88 
SIR J. B. LAWES AND PROFESSOR J. H, GILBERT OX THE 
“ S’il est er} physiologie un fait parfaitement demontre, c’est celui de la non assimi¬ 
lation de I’azote libre par les vegetaux, et je puis ajouter par les plantes d’un ordre 
inferieur, telles que les raycodermes, les cliampignons/' 
Thus, then, although by the terms of our inquiry, Boussixgault’s attention was 
specially directed to the evidence of gain of nitrogen from the air by the soil which 
his experiments in 1858 and 1859 afforded, he, in 1876 sta.tes that he is not aware 
of any irreproachable observation establishing the reality of such an action, whilst, on 
the contrary, he considers it established that soils emit rather than gain free nitrogen. 
Further, he considers it perfectly demonstrated, that neither plants of a higher, nor 
those of an inferior order, such as mycoderms and fungi, assimilate free nitrogen. 
It is to be observed that, although Boussingault clearly ignores the significance of 
the results to which we had directed his attention, he did not offer any explanation of 
them. Subsequently, on several occasions when passing through Paris, one of us 
sought to meet M. Boussixgault, and to discuss the question with him further, but 
he was each time in Alsace. However, one of us visited him at Liebfrauenberg in 
1883, and had an interesting conversation with him on the subject. ISlo special 
reference was made to his experiments of 1858 and 1859 ; but he clearly maintained 
the same view as to the non-fixation of free nitrogen, as given in the sentences above 
quoted from his letter of 1876. 
It is remarkable, that in that letter he should so expressly give his opinion against 
the supposition that the lower organisms within tlie soil effect the fixation of free 
nitrogen, notwithstanding the evidence of his experiments of 1858 and 1859 that the 
gain, if there really were gain, was chiefly by the soil, and chiefly as organic matter, 
the accumulation of which he attributed to the development of mycodermic vegetation. 
It is true that, in the discussion of the results, he did not give any clear indication 
whether he considered that the apparent fixation was due in the first instance to the 
process of nitrification, the mycoderms only appropriating the nitrogen of the nitrates 
formed, or whether he supposed that the mycoderms themselves were the primary 
agents, and that the nitrification was only the result of the oxidation of the myco¬ 
dermic remains. 
It did indeed seem, that, in the results in question, there was the germ of the germ 
explanation of the fixation of free nitrogen, if such took place at all, in connection 
with vegetation. But we confess that Boussingault’s very distinct conclusion 
against the assumption of any srtch agency, notwithstanding the indications of some 
of his own experiments, leads us still to ask for further confirmation of the evidence 
of others in the same direction, which has been accumulatino^ during the last few 
years. 
