462 MR. J. B. LAWES, DR. GILBERT, AND DR. PUGH ON 
of atmospheric ammonia had been ascertained, the influence of that source may, in the 
case of these new results, be entirely overlooked. 
The fact that a given amount of Nitrogen in the form of combination of a nitrate was 
more efficacious than the same amount supplied in either of the ammoniacal salts expe- 
rimented upon, was held to show that the nitrate was taken up by the plants as such, 
and was not previously transformed into ammonia. 
M. Vitiz’s experiments, as a whole, thus indicated that plants can take up Nitrogen 
in three forms—namely, as nitric acid, as ammonia, and as free Nitrogen. He enume- 
rates the following conclusions :— 
1. By means of nitre we may prove, without the aid of an enclosing apparatus, that 
plants absorb and assimilate the gaseous Nitrogen of the atmosphere. 
2. Nitre acts by its Nitrogen. It is absorbed in the state of nitre. 
3. In relation to the amount of Nitrogen, nitre is more active than ammonia-salts. 
9. M. G. Viute’s collateral experiments to control or explain his results*. 
M. Viuiz adduces evidence of yet another kind, in support of his view that plants 
assimilate the free Nitrogen of the air. Air was passed through an otherwise closed 
apparatus, in which was placed a vessel containing calcined sand, or calcined sand 
and decomposing organic‘matter. In no case was nitric acid formed. Nitrification, the 
result of the combination of the oxygen and nitrogen of the air within the porous soil, 
was not, therefore, the source of the Nitrogen gained by his experimental plants. 
Experiments were made in which a given amount of organic matter (Lupins, Gelatine, 
&c.) was mixed with calcined sand, and exposed in an apparatus to a current of air, 
which carried the gaseous products into acid, to retain any ammonia that might be 
formed. The determination of the Nitrogen remaining in the matrix, and of the ammonia 
given off and absorbed by the acid, showed a loss of Nitrogen, which could only have 
passed away in the free gaseous form. 
Other vessels of sand were prepared, to which similar known amounts of organic 
matter were added, and then seeds of Wheat were sown, the organic matter serving as 
manure. When the growth was stopped at a certain stage, almost exactly the same 
amount of Nitrogen was found in the Wheat plants and in the sand, &c., as was origin- 
ally contained in the seeds sown and in the organic matter added. Assuming that the 
decomposition of the organic matter had taken the same course as in the other experi- 
ments—free Nitrogen being given off—it was obvious that a corresponding amount of 
free Nitrogen had been taken up by the plants. In other cases the growth of the 
Wheat was allowed to continue longer than in the experiments just alluded to; and 
then the total Nitrogen in the products not only equalled, but considerably exceeded, 
that in the seed sown and in the organic manure. In this instance, at least, it could 
not be said that the Nitrogen not received by the plant as ammonia had been taken up 
by it as nascent Nitrogen evolved in the decomposition. 
* Recherches Expérimentales sur la Végétation, 1857. 
