proved to be that plant, which had been so changed by 
growing in the dark. Indeed it was recollected, that 
some soil had been taken into the drain from a neigh- 
boring garden, some time’before it was found so altered. 
t n ascertained, by experiment, that the green 
color of vegetables may be produced by the light of a 
lamp, in the absence of the more perfect light of the 
sun; as discovered sad i Abbe Tessier. 
Leaves give out moisture by their wnder surface, in 
proportion to the net of light, Bee not of heat; so 
that th g the night. 
The water which ete es from vegetables. i is not pure, 
but serves as the vehicle of the aroma; it is equal to the 
third part as their weight every twenty-four hours, in 
healthy plan 
Leaves 2 expose the sap which they receive from 
the wood, to the action of the air, and return it again 
to the bark by its fibres or vessels. They also serve to 
ere is scarcely aD. 
the ear 
without any other assistance than the contact of w 
be seen every day, in the Hyacinth, 
a 
pieces, as well as gramineous, or grassy plan 
wheat, &c. raised in saucers or bottles, containing mere 
"tn vegetables, hydrogen is the principle which fixes 
itself, while orygen gas (the other constituent part of 
water) makes it escape. 
But although pure water is more proper for vegeta- 
tion, than water “sem, ate with pale xs Nera! a. - 
posed 
fis tnd remains ot ¥6 
y charging it 
of those juices already formed, the nitrogen gas (which 
has already been mentioned, as constituting one of the 
nutritive principles x plants) is abundantly afforded 
by the alteration of vegetables and animals, an 
facilitate their development 
P este : has been Sar by various experiments, 
r is sufficient to the support of plants, we 
maust = nae consider the earth as of no use; 
; it is the reservoir destined 
nature ie te preserye the encgag:s juice Snide the 
d 
d must 
a 
Z NE an ER 
ee 7 ue iu ine 
The nature of the soil must be varied accordingly as 
the plant requires a more or less considerable raed 
of water, in a given time; and accordingly as its roots 
extend to a greater or less ath Every kind of earth 
is not suitable for every p ; and, consequently a 
slip cannot be grafted, rent upon every species. 
oper soil is one w affords a sufficiently firm 
i) 
water sufficiently, that the plant may 
not be without it when wanted. 
To answer these several conditions, it is necessary to 
make a proper mixture of the primitive earths, for none 
of them in particular possesses them. 
Silicious (white sand) and Calcareous (limy) ma; 
considered as hot and drying; the Argillaceous (clayey) 
bsorbs water, but 
it; calcareousearth receives and gives it out quickly ; 
7 £ +f ow o 
that they correct each other by intermixture. 
ingly we find, that, by adding lime to an argillaceous 
earth, this ‘ask is divided ; and the drying property of 
the lime is mitigated, at the same time that the stiffness 
of the clay is diminished. 
Saline substances have been supposed of importance 
s-may, however, be of use to vegetation, 
though not essential to it. That of common salt ma 
— st plants as it does upon the human body, by 
to digest the food, without furnishing nutri- 
qe ae 
It is upon this principle, I presume, that common table 
salt mixed with water in a flower vase, will expedite the 
opening of a rose-bud, or other flower, when plucked 
from the parent branch. 
Here I will observe, that if a small bit of nitre be 
added to the pure water, in a vase containing flowers; 
the water changed every day, and a small piece of the 
flower-stalk cut off each time of the change of water, 
the freshness of the flowers may be preserved for a con- 
siderable length of time. 
Secretions.—The sap, when exposed to the action of 
the air, light, and heat, by the leaves, becomes a new 
, which assumes the peculiar flavor and qualities 
. < plant. Gum is one secretion, which oozes from 
he cherry, and other trees, resin and turpentine, are of 
