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On the Food of Plants. 321 
triment of silkworms, will again, in a raphe daysidb be covered 
thick with foliage. 
Adanson, in his account of Plshtl informs us, that 
** when every thing green has been devoured by. locusts, not 
‘a vestige of their destructive progress, after a few days, can 
be discovered.” He 
From the consideration of these and» other facts» similar 
to them, many distinguished chemists have: delivered wit 
as their opinion that water is decomposed by vegetables. 
M. Chaptal says, “ La décomposition de l’eau est prouvée 
non seulement dans le vegétal mais dans lanimal.”’ And 
for this Jast he quotes the authority of Rondelet. 
That water, as such, enters largely into the compositionof 
vegetables, is evident; but whether or not, and to what extent, 
it is decomposed, has not, as lL apprehend, been yet demons 
strated. In water meadows, with a plentiful supply of ruan- 
ning water, vegetation proceeds even in the depth of winter, 
and during the scverest frosts ; but stagnant water is at all 
times unfriendly to our meadows. Any given quanitity may 
remain upon the surface for weeks or months subject to de- 
composition ; but instead of being in this state beneficial, it 
is injurious to our crops. In our water meadows we uni- 
versally observe that it is not humidity which dees good, but 
a thick sheet of water flowing incessantly, night and day, 
(for a certain period) over the surface. 
Hence it seems probable that water is essential to the 
growth of plants, not merely as such, but as it proves a 
vehicle of other substances which are their proper food. 
If we may form a judgment from their analysis, carbon 
may be regarded as the chief pabulum of plants; and this 
we know can, ina given proportion, be conveyed ‘to’ them 
by water. M. Chaptal is not only of opinion that carbonic 
acid is essential to their growth, but he affirms that the base 
of this acid contributes to the formation of the vegetable 
fibre. In support of this opinion he observes, that in fungi, 
which live in subterrancous places, this acid abounds 5 but 
by bringing them from almost perfect darkness gradually to 
the light, this acid disappears, and the fibres proportionably 
increase, This opinion is confirmed by some experiments 
Vol. 26. No. 104. Jan. 1807. X of 
