THE SOURCES OF THE XITROGEX OF VEGETATION, ETC. 403 



The general conclusions from this part of the inquiry were as follow : — 



1. Organic matters in decomposition lose a part of their Nitrogen as ammonia, and a 

 part as Nitrogen gas. 



2. Vegetation does not interfere with the progress of this decomposition. 



3. Plants cultivated in a manured soil, give more Nitrogen in their produce than the 

 manure yields as ammonia. 



4. The excess of Nitrogen in the produce has been absorbed as free gaseous Nitrogen. 

 In regard to the explanation of the assimilation of free Nitrogen by plants, M. Ville 



calls attention to the fact, that nascent hydrogen is said to give ammonia, and nascent 

 oxygen nitric acid, with free Nitrogen ; and he asks — Why should not the Nitrogen in 

 the juices of the plant combine with the nascent carbon and oxygen in the leaves 1 He 

 further refers to the supposition of M. de Luca, that the Nitrogen of the air combines 

 with the nascent oxygen given off from the leaves of plants, and forms nitric acid. Again, 

 the juice of some plants (mushrooms) has been observed to ozonize the oxygen of the 

 air ; is it not probable, then, that the Nitrogen dissolved in the juices will submit to the 

 action of the ozonized oxygen with which it is mixed, when we bear in mind that the 

 juices contain alkalies, and penetrate tissues the porosity of which exceeds that of spongy 

 platinum, a body so apt to favour combinations ? 



Summary Statement of the results and conclusions ofM. Boussingavlt and M. G. Ville. 



M. Boussingault, when, in his earlier investigations, he grew plants in free air, found 

 only such indications of a gain of Nitrogen as, in his opinion, may be attributed to 

 inaccuracies in the methods of experimenting and analysis at the early date, and to the 

 combined influences of ammonia and organic corpuscles in the atmosphere ; and when, 

 more recently, he grew plants only shaded in such a manner as still to allow the free 

 access of air, the gain of Nitrogen observed was not more than he considered might be 

 due to the influences last mentioned. When he grew plants, either in confined and 

 limited volumes of air, or in a current of air washed free from ammonia and organic 

 corpuscles, the results did not show any appreciable gain of Nitrogen. Lastly, when 

 he supplied either decomposing organic matter, or nitrate, to increase the activity of 

 growth, he did not find such an amount of combined Nitrogen in his products, as to 

 lead him to conclude that there had been any assimilation by the plants of free or 

 uncombined Nitrogen. In these cases, indeed, he generally found a loss of combined 

 Nitrogen during the experiment, supposed to be due to the evolution of free Nitrogen 

 in the decomposition of the matters used as manure. 



The results of M. G. Ville, on the other hand, showed a very considerable gain of 

 Nitrogen during growth, whether the plants were subjected to a current of unwashed 

 ah - , or of ammonia-free air, — and also when the plants were grown in free air, and their 

 activity of development increased by the use of nitrates, or other nitrogenous matters, 

 as manure. This gain of Nitrogen he considers to be due to the assimilation of free or 

 uncombined Nitrogen. It is remarkable, too, that the proportion of Nitrogen gained, to 



mdccclxi. 3 s 



