• r )l'_l MK. .1. It. I,\U i;s. DB. GILBEBT, MSB DB. FUGH OK 



Bite apparatus Bufficientlj air-tight, was not followed up to the extent which had 



intended. 



The plan proposed was, to place the organic matter in an atmosphere of pore 

 and to afford a constant supply of the gas as it became converted into cai bonic and. and 

 was absorbed by a solution of caustic potash. 



The results obtained go to show that, in the presenci of free oxygen, Nitrogen gas is 

 evolved. But as the investigation is as yet so incomplete, owing to the circumstance 

 above alluded to, we prefer not to give the results until we can confirm them by a more 

 extended series of experiments under more favourable conditions. 



Taking together the results of all the experiments which have been made upon the 

 decomposition of nitrogenous organic matters, the) obviously point I ous difficulty 



in the way of experiments made upon the question of the assimilation of free Nit. _ 

 by plants. It is not possible to conduct any such experiments without exposing nitro- 

 genous organic matter to conditions more or less analogous to those under which the 

 loss of Nitrogen recorded in Tables VII. and IX. took place. For although, as Bous- 

 SINGAULT has shown, there may be no loss of Nitrogen during germination, yet, during 

 the entire period of the growth of a plant, certain portions of the vegetable substance 

 may be subjected to conditions favourable to the decomposition of its nitrogenous com- 

 pounds, and to the evolution of free Nitrogen. 



As illustrative of how far these conditions are likely to be operative in the manner 

 indicated, the following results, made with Wheat, Barley, and Oats respectively, are 

 ■very instructive. Seeds of the three plants were sown, eacli in precisely the same 

 kind and amount of soil, &c, as employed in the experiments on the assimilation 

 question. The three pots were placed beneath a large glass shade, 16 inches in diameter, 

 which fitted into the groove of a stone-ware lute-vessel, into which sulphuric acid was 

 poured to exclude the access of external ah - . The whole stood on a table in the diffused 

 light of the laboratory. The plants were at first supplied with distilled water; but 

 with no carbonic acid beyond that which might be contained in the water. These con- 

 ditions afforded all that was necessary for germination and growth, with little oppor- 

 tunity for the assimilation of free Nitrogen, even were this possible in the more favour- 

 able conditions of sunlight. Yet the conditions were more than ordinarily favourable 

 to the decomposition of nitrogenous compounds, provided this would take place, under 

 certain circumstances, during the growth of the plant. The succulent character of the 

 stems and leaves so grown in the shade, would render the nitrogenous matters more 

 liable to decomposition than in the case of the more firm and hardened stems of plants 

 grown in sunlight. 



Eight seeds of each plant were sown ; and in a few days all came up. and grew very 

 rapidly in height, without much tendency to development and expansion of leaf. The 

 plants were all very much alike — tall, slender, delicate, and having the peculiar pale- 

 green colour common to plants deprived of sufficient sunlight. In several other expe- 



