NETTLE. 213 
young branches of the alder, cut down in the summer, 
spread over the fields, and left during the winter to de- 
cay, are found to answer the purpose of manure. The 
fresh gathered leaves, being covered with a glutinous 
moisture, are said to be sometimes strewed upon floors 
to destroy fleas, which become entangled in it, as birds 
are with bird-lime. But these agile and troublesome 
insects must be numerous indeed to render the setting 
of traps for them of any avail towards their destruction* 
230. The COMMON NETTLE. There are two kinds of 
nettle common in England, one of which (Urtica dioica) has 
heart-shaped leaves, and the other (Urtica urens) has oval leaves. 
Although generally considered a noxious weed, the 
nettle is a plant of extensive utility. By the country 
people the young and tender leaves and tops are boiled 
for food, and are eaten as a substitute for greens and 
other pot-herbs. Asses eagerly devour the leaves of 
nettles ; and if these be boiled, and mixed with other 
food for poultry, they are said to promote their laying 
of eggs. A kind of rennet is made in the Highlands 
of Scotland, by adding a quart of salt to three pints of 
a liquor produced by the boiling of nettles. A table- 
spoonful of this is said to be sufficient to coagulate a 
bowl of milk. From the fibrous stalks of the netde, 
dressed in the manner of flax or hemp, cloth and paper 
may be made. The manufacture of these has been 
pursued with success in some parts of the Continent; 
and in our own country a coarse kind of canvass has 
been produced from them. The roots, when boiled, 
communicate a yellow colour to woollen cloth, linen, 
and cotton. 
It must be remarked that the stings of nettles, when 
examined by a microscope, are shown to be extremely 
curious objects. They consist of a slender, tapering, 
sharp, and hollow substance, with a minute hole at the 
point, and a bag at the base. When the sting is pressed, 
it perforates the skin, and the same pressure forces up 
from the bag, into the wound, a corrosive liquor, which 
