10 
ON CHEMISTUY. 
may be fairly hazarded, that this energetic fluid is the prime, if not 
the entire source of all the vegetable developements; I mean in as much 
as nutrition is concerned. A difficulty remains in respect to carbon, 
for the chemical destructive analysis of vegetable bodies, seems to 
prove that, the bulk of their substance is resolvable into carbonace¬ 
ous matter. The inquiry must be pursued when carbon becomes the 
subject of investigation. However, as water is incapable of dissolv¬ 
ing charcoal, at least in any appreciable quantity; and as it is cer¬ 
tain that not a particle of solid carbon, however impalpable it 
may be, can enter the absorbent processes of the roots; it can 
scarcely be supposed that the carbon of the plant is derived from in- 
trosusception by the roots. But the physiological chemist may say, 
that it is in the germ of carbonic acid that carbon is introduced ! 
Others of a more modern school will refer the process of nutritive 
absorption to the formation of a substance said to be recently disco¬ 
vered, termed humine ! Carbonic acid, doubtless may be detected in 
the juices of plants, but it is in all probability a result of electric vi¬ 
tal action within the cells, and not one of simple absorption from the 
ground. The fact is, that carbon does not exist in the living plant; 
it is never detected but by destructive chemical action ; or by fer¬ 
mentation after the extinction of the vital principle. Water there¬ 
fore may be considered the pabulum of vegetable developement and 
growth without difficulty, and I deem it to be such, not perhaps in its 
crude native form, but modified by the agency of the substances within 
the soil, which become decomposed in the immediate vicinity of the 
roots. To produce the food of plants, all the great natural agents 
are of necessity employed, and water is the medium through which 
they act. It may indeed be itself decomposed, and by its elements 
produce new compounds with the decomposable substances it meets 
with; but whatever be its agency in the soil, the exciting cause ap¬ 
pears to be the vital principle, which, stimulating the otherwise dead 
and effete matters in the soil, causes the plant to attract, or at least 
to receive from them, a simple, bland, colourless sap, that is mo¬ 
dified and changed by other agencies within appropriate vascular or¬ 
gans, till at length it becomes assimilated into the substance of the 
organised being which has excited and perfected these astonishing 
mutations. The reader, the more deeply he reflects, the more per¬ 
tinaciously he investigates, will, in proportion, be inevitably convin¬ 
ced, that our knowledge is but perfect ignorance; and that however 
deeply read we may be in what concern effects of causes we are still 
in the dark; and that search how we mav, they elude our utmost 
vigilance. 
October \lth, 1833. 
