March.] THE NURSERY. 287 
In Sicily the three species above mentioned, with the view of ob- 
taining manna from them, but. more particularly the first, are plant- 
ed on the declivities of hills, having eastern aspects. After ten 
years growth, the trees first begin to yield manna, but they require 
to be much older, before they afford it in any considerable quantity. 
Although the manna exudes spontaneously from the trunks and 
branches, yet in order to obtain it more copiously, incisions are 
made through the bark, by means of a sharp crooked instrument; 
a slice of which, is taken off, about three inches in length and two 
in breadth; they leave the wounds open, and by degrees the manna 
runs out. The season thought to be most favourable for instituting 
this process, is a little before the dog-days commence, when the 
weather is dry and serene. The incisions are first made in the 
lower part of the trunk, and repeated, at the distance of an inch or 
two from the former wound, still extending them upwards as far as 
the branches, and confining them to one side of the tree; the other 
side being reserved till the year following, when it undergoes the 
same treatment On making these, a thick white juice immediate- 
ly begins to flow, which gradually hardens on the bark, and in the 
course of eight days, acquires the consistence and appearance, in 
which the manna is imported; when, it is collected in baskets, and 
afterwards packed in large chests. Sometimes the manna flows in 
such abundance from the incisions, that it runs upon the ground, by 
which it becomes mixed, with various impurities, unless prevented, 
which is commonly attempted, by interposing large concave leaves, 
stones, chips of wood, &c. The business of collecting it, generally 
terminates in those countries in September, when the rainy season 
sets in. 
That manna is got in quantities on the leaves of trees, is an opi- 
nion taken from the doctrine of the ancients, and received as in- 
contestible without consulting nature; for all those who are em- 
ployed in the gathering of it, know of none that comes from the 
leaves; therefore, that with which the Israelites were so peculiarly 
favoured, could only have been produced through miraculous means, 
and is consequently out of the province of the naturalist. The best 
manna is what exudes from the tree very slowly, and is collected 
clean; this is always more dry, transparent, and pure; for when 
it flows copiously it concretes into a coarse, brown, unctuous mass. 
Methods of propagating Trees and Shrubs by Layers. 
There are few trees or shrubs, if any, but may be increased in 
this way. The nursery gardeners who want to propagate large 
quantities of various hardy kinds, of which they cannot easily pro- 
cure seeds, and which by experience they do not find to grow free- 
ly by cuttings; establish, what they call, stools, of the different kinds 
intended to be propagated, particularly of the deciduous tribe, and 
also, some evergreens. For this purpose, they plant in different 
quarters, stout healthy plants, at the distance of four or five feet 
from one another every way, and head them down; these throw 
out near the earth a number of young shoots, some of which may 
