288 THE NURSERY. [March. 
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 oft", 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 
w^eather 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 flovvs in 
such abundance from the incisions, that it runs upon the ground, 
by which it becomes mixed with various impurities, unless pre- 
vented, 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 
opinion 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 
freely 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 
be laid in the autumn or spring following; these stools, as they are 
commonly called, continue for many years, always laying down 
the shoots of the last season, and every year successively they pro- 
duce abundance for the ensuing year's laying, still taking them off" 
either in autumn or spring as they become well I'ooted. The elm. 
