ASPECTS OF AN OLD AGRICULTURAL QUESTION. 267 



organisms of the leguminosae, or the symbiotic unions of 

 algae and bacteria, resolves itself into one, viz. ; the ques- 

 tion of living cells under certain conditions where they can 

 destroy large quantities of carbon compounds, being able to 

 obtain the energy necessary to enable them to force free 

 nitrogen to combine with some of the products. 



If this is so, it seems to me there is a question definitely 

 stated for chemistry to attack. The known inertness of the 

 nitrogen molecule seems to have had much to do with 

 discouraging chemical investigation along these lines, and 

 I am told that practically no grounds exist for a deductive 

 explanation of any such process as this seems to imply. Of 

 course we must not forget that objections to hypothetical 

 explanations of physiological experiments have usually been 

 urged at similar periods to that which the nitrogen question 

 is in, and have done good service ; but occasionally, as with 

 Liebig's scepticisms concerning the respiration of plants as a 

 physiological process, persistence in the demonstration that 

 a given result, inexplicable from the chemical point of view, 

 really does take place in the living cell, leads to valuable 

 advances in knowledge. 



Evidence has been given to show (33) that we cannot 

 explain the matter by reference to the newly-discovered 

 constituent of the atmosphere, Argon ; and it seems certain 

 that the problem is, at present, insoluble. 



At the same time, we must not forget that there 

 are plenty of other cases where the living protoplasmic 

 machinery of a cell carries out analytic and synthetic 

 changes, with economy, which are either inimitable in the 

 laboratory, or only possible at high temperatures, or under 

 conditions which make it mysterious how the cell manages to 

 do the work with, apparently, so small an expenditure of 

 energy — I say apparently, because of course the energy 

 necessary to do the work is the same in both cases, only in 

 the laboratory much has to be wasted owing to the methods 

 of application. 



These facts point to a question of the mode of present- 

 ment, so to speak, of the molecules concerned, and, no 

 doubt, the chemist will soon learn some method of so bring- 



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