THE SOUKCES OF THE NITEOGEN OF VEGETATION, ETC. 541 



the range of conditions possibly favourable for the assimilation of free Nitrogen was, 

 therefore, more limited. But the results recorded with these plants, so far as they go, 

 do not indicate any assimilation of free Nitrogen. Since, however, in practice, Legu- 

 minous crops assimilate, from some source, so very much more Nitrogen than Grami- 

 naceous ones, under ostensibly equal circumstances of supply of combined Nitrogen, it 

 is desirable that the evidence of further experiments with these plants, under conditions 

 of more healthy growth, should be obtained. 



Results obtained with some other plants are in the same sense as those obtained with 

 Graminacese and LeguminosBe, in regard to the question of the assimilation of free 

 Nitrogen. 



In view of the evidence afforded of the non-assimilation of free Nitrogen by plants 

 under the wide range of circumstances provided in the experiments, it is desirable that 

 the several actual or possible sources of combined Nitrogen to plants should be more 

 fully investigated, both qualitatively and quantitatively. 



If it be established that the processes of vegetation do not bring free Nitrogen into 

 combination, it still remains not very obvious to what actions a large proportion of the 

 existing combined Nitrogen may be attributed. 



