THE SOURCES OF THE NITROGEN OF VEGETATION, ETC. 527 
A reference to Table XII. will show the numerical results of this experiment with 
beans in 1857. 
The beans and peas of 1858, the particulars of which are also given in Table XII, 
did not grow so satisfactorily as the beans of 1857, last noticed. Yet the beans of 
1858 gave more than three times as much organic matter in the produce as was con- 
tained in the seed, and they appropriated even a much larger proportion of the Nitrogen: 
of the seed than did those of 1857. The result with the peas was not so satisfactory, 
owing to the less healthy character and the more limited amount of their growth. 
From the fact that these Leguminous plants did not go through a complete course of 
growth to the flowering process, it may be objected that hence they did not pass certain. 
stages of growth in which they might possibly assimilate free Nitrogen. We shall refer 
to this objection again further on. At present we confine attention to the important 
fact, that active growth has taken place—that the process of cell-formation, with the 
accompanying one of the decomposition of carbonic acid and the fixation of carbon, has 
gone forward with a deficient supply of combined Nitrogen, and in the immediate pre- 
sence of free Nitrogen, and yet none of it has been assimilated. The plants have in fact 
been subjected to a considerable range of the conditions which were considered, & priori, 
to be favourable to the assimilation of free Nitrogen; and yet this has not taken place. 
It is a fact observed in agriculture, that manures rich in organic matter frequently 
favour the growth of Leguminous crops. We shall not here discuss the question 
whether these organic manures, as such, act simply as a source of carbonic acid, or of 
carbon compounds of a more complicated character. "We would, however, call attention 
to the fact that, in the case of the experiments now under consideration, the vital forces 
were sufficiently energetic to perform the function of cell-development and multiplica- 
tion, from carbonic acid as its source of carbon; yet these forces, capable of effecting 
this result, have been incapable of effecting the appropriation of free Nitrogen. 
Buckwheat. 
The evidence afforded by the numerical results in the Table XII. relating to this 
plant is not of so decisive a character as that with regard to the cereals, or even to the 
Leguminous plants; for the quantity of dry matter in the produced plants is less than 
that in the seed sown, whilst the Nitrogen in the plants is little more than one-third 
that of the seed. But when we come to compare the results of the experiments with 
Buckwheat grown with and without the supply of ammonia, it will be found that the 
physiological evidence of the dependence of vegetable growth upon a constant supply of 
combined Nitrogen is stronger in the case of these plants than in that of the cereals. 
The small proportion of the total Nitrogen of the seeds which the buckwheat seemed 
capable of appropriating might lead to the inference that, ceasing to grow with an 
abundance of combined Nitrogen apparently at its disposal, it had done so for some 
other reason than the want of available Nitrogen. But this question was set at rest by 
the fact that, on the addition of an amount of ammonia very small in its contents of 
MDCCCLXI. 4¢ : 
