QUESTION OF THE SOURCES OF THE NITROCEN OF VEGPH’ATTON. 35 
centrated—indeed of a strength not at all comparable with that of root-sap. Then, 
the soils, the results relating to which he gives, were extremely rich in nitrogen, and 
in this respect again bear no comparison with the subsoils from which the lucerne, 
and other plants experimented upon at Rothamsted, are supposed to have taken up 
much nitrogen. 
Thus, whilst in Loges’ experiments, one of the soils acted upon contained 0’804, 
and the other 0'367 per cent, of nitrogen, the surface soil of the lucerne plot at 
Rothamsted which yielded such large amounts of nitrogen in the crops contained 
little more than 0‘120 per cent., and the subsoil from which a large quantity of the 
nitrogen must have been derived, only from 0'04 to 0’05 per cent. Again of the 
0'804 per cent, in the one soil, 0‘322, or 40 per cent, of the whole was taken up by 
the acid, and of the 0'367 per cent, in the other soil, 0’083 or 22‘6 per cent, of the 
whole was taken up. In the richer soil the relation of carbon to nitrogen was as 
13’78 to 1, and in the other as 11'74 to 1, whilst the relation of carbon to nitrogen 
in the hydrochloric extract was in the case of the richer soil 6’8 to 1, and in that of 
the other about 11 to 1. 
By phospho-tungstic acid Loges obtained precipitates from the acid extracts, which 
in the case of the richer soil showed only 6'67, and in that of the other 5'74 carbon 
to 1 of nitrogen. In reference to these results, it may be observed that this is 
approximately the relation of carbon to nitrogen in the raw clay subsoil at 
Rothamsted below the depth at which it is materially affected by manuring or 
cropping. 
Thus, we have found the proportion of carbon to nitrogen to be in the surface soil 
of rich prau’ie, or permanent grass land, between 13 and 14 to 1 ; in that of some¬ 
what exhausted arable surface soil, between 10 and 11 to 1 ; and in raw clay subsoil 
about 6 to 1. 
Loges states that he has experimented on a great variety of soils, and that he has 
found in all, without exception, that the hydrochloric acid extract gives the phospho- 
tungstic precipitate; and he hopes soon to be able to report further on the nature of 
the highly nitrogenous humic compound obtained. It would thus seem, however, to 
be an amide or peptone body. 
It is of much interest that the nature of the nitrogenous body existing in, or 
dissolved out of, soils and subsoils should be determined ; and to this end it seems 
desirable to act on soils with stronger acids than those hitherto employed in our own 
experiments. But results so obtained can obviously have only an indmect bearing on 
the special question we have in view, namely—whether roots do, by virtue of their 
acid sap, attack the otherwise insoluble organic nitrogen of the soil and subsoil, and 
either take it up as such, or bring it into a condition in which it is easily susceptible 
to further change, and so rendered available as a source of nitrogen to the plant ? 
Still more recently, MM. Berthelot and Andre (‘Compt. Rend.,’ vol. 103, 1886, 
p. 1101,) have published the results of experiments to determine the character of the 
