ng plaster placed
over them.

842. Leeches and their Application.

The leech used for medical purposes is called the _hirudo medicinalis_
to distinguish it from other varieties, such as the horse-leech and
the Lisbon leech. It varies from two to four inches in length, and is
of a blackish brown colour, marked on the back with six yellow spots,
and edged with a yellow line on each side. Formerly leeches were
supplied by Lincolnshire, Yorkshire, and other fenny countries, but
latterly most of the leeches are procured from France, where they are
now becoming scarce.

843. When Leeches are Applied

When leeches are applied to a part, it should be thoroughly freed from
down or hair by shaving, and all liniments, &c., carefully and
effectually cleaned away by washing. If the leech is hungry it will
soon bite, but sometimes great difficulty is experienced in getting
them to fasten. When this is the case, roll the leech into a little
porter, or moisten the surface with a little blood, or milk, or sugar
and water. Leeches may be applied by holding them over the part with a
piece of linen cloth, or by means of an inverted glass, under which
they must be placed.

844. When applied to the Gums

When applied to the gums, care should be taken to use a leech glass,
as they are apt to creep down the patient's throat: a large swan's
quill will answer the purpose of a leech glass. When leeches are
gorged they will drop off themselves; never _tear_ them off from a
person, but just dip the point of a moistened finger into some salt
and touch them with it.

[ILL-NATURE SUCKS POISON FROM THE SWEETEST FLOWER.]

845. Quantity Removed.

Leeches are supposed to abstract about two drachms of blood, or six
leeches draw about an ounce; but this is independent of the bleeding
after they have come off, and more blood generally flows then than
during the time they are sucking. The total amount of blood drawn and
subsequently lost by each leech-bite, is nearly half an ounce.

846. After Leeches Come Away,

After leeches come away, encourage the bleeding by flannels dipped in
hot water and wrung out dry, and then apply a warm spongiopiline
poultice. If the bleeding is not to be encouraged, cover the bites
with a rag dipped in olive oil, or spread with spermaceti ointment,
having previously sponged the parts clean.

847. When Bleeding C