On the Sources of the Nitrogen of Vegetation. 529 
which seem to differ so widely in their relations to the combined 
nitrogen supplied within the soil—and finally, to have some of the 
same descriptions as those experimented upon by M. Boussingault, 
and M. G. Ville, with such discordant results. 
' Thirteen experiments were made (4 in 1857 and 9 in 1858), in 
which the plants were supplied with no other combined nitrogen 
than that contained in the original seed. In 12 of the cases pre- 
pared soil was the matrix, and in the remaining one prepared 
pumice, _ 
_ Of 9 experiments with Graminaceous plants, 1 with wheat and 2 
with barley were made in 1857. , In one of the experiments with 
barley there was a gain of 0-0016, and in the other of 0:0026 gramme 
of nitrogen. In only two cases of the experiments with cereals in 
1858, was there any gain of nitrogen indicated; and in both it 
amounted to only a small fraction of a milligramme. Indeed, in no 
one of the cases, in either 1857 or 1858, was there more nitrogen in 
the plants themselves, than in the seed sown. A gain was indicated 
only when the nitrogen in the soil and pot—which together weighed 
about 1500 grammes—was brought into the calculation. Moreover, 
the gain only exceeded 1 milligramme in the case of the experiments 
of 1857, when slate, instead of “elazed earthenware stands were used as 
the lute vessels; and there was some reason to believe that the gain 
indicated was due to this circumstance. In none of the other cases 
was the gain more than would be expected from error in analysis. 
The result was then, that in no one case of these experiments was 
there any such gain of nitrogen as could lead to the supposition that 
free nitrogen had been assimilated. The plants had, however, vege- 
tated for several months, had in most cases more than trebled the 
carbon of the seed, and had obviously been limited in their growth 
for want ofa supply of available nitrogen in some form. During this 
long period they were surrounded by an atmosphere containing free 
nitrogen ; and their cells were penetrated by fluid saturated with that 
element. It may be further mentioned, that many of the plants 
formed glumes and palese for seed. 
It is to be observed that the resultseof these experiments with 
cereals go to confirm those of M. Boussingault. 
The Leguminous plants experimented upon did not grow so 
healthily under the artificial conditions as did the cereals, Still, in all 
three of the cases of these plants in which no combined nitrogen 
was provided beyond that contained in the original seed, the carbon 
in the vegetable matter produced was much greater than that in the 
seed—in ¢ one instance more than 3 times greater. In no case, how- 
ever, was there any indication of assimilation of free nitrogen, any 
more than there had been by the Graminaceous plants grown under 
similar circumstances. 
One experiment was made with buckwheat, supplied with no other 
combined nitrogen than that contained inthe seed. The resuit gave 
no indication of assimilation of free nitrogen. 
In regard to the whole of the ‘experiments in which the plants 
were supplied with no combined nitrogen beyond that contained in 
Phil. Mag. S, 4, No, 148, Suppl. Vol. 21. 1 ee 
