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LYMPHATIC VESSELS OF THE HEAD AND
NECK.

By albert p. BKUBAKER, A.M., M.D., D.D.S.

THE LYMPHATICS.
The Lymphatics, and the glands in connection with tliem, consti-
tute a system of vessels most important to the nutrition of the body.
In all the vertebrate animals this system is superaddetl to the circula-
tory, and is designed to carry back into the general blood-current the
excess of nutritious fluid which has been exuded from the capillary
blood-vessels for the ])urposes of nutrition. The fluid which the lym-
phatic vessels contain is known as lymph, and resembles in its physical
and chemical constitution the liquor sanguinis or blood-})lasma.
The lymphatic vessels have a very extensive distribution, being found
in nearly all the tissues and organs of the body which receive blood.
They are absent, or at least have not yet been discovered, in the hair,
nails, epidermis, and other structures usually regarded as non-vascular.
Lymphatics are widely distril)uted throughout the body, but are more
abundant in some situations than in others. The inner surfaces of the
limbs are more abundantly supjflied than the outer surfaces, while the
lines of junction of the limbs with the trunk are especially rich in both
vessels and glands. In the thoracic and abdominal cavities they are
very numerous. In the majority of situations in which the lymphatics
are found they are arranged into a superficial and a deej) set, the former
being very fine and situated in and beneath the skin and nuicous mem-
branes, while the latter are nuich larger and folloAv the course of the
large blood-vessels.
The- lymph, when examined microscopically, is seen to consist of a
clear colorless plasma, in which are imbedded an immense number of
corpuscular elements. The lymph which has been ol)tained from man
and inferior animals is usually colorless and transj)arent, although at
times it presents a faintly yellowish hue. It is odorless, slightly saline
in taste, alkaline in reaction, and possesses in the dog a specific gravity
of 1022. Like the blood, lymph undergoes a spontaneous coagulation
wdien withdrawn from the body, although the coagulum is never so firm
as in the case of the blood. In its chemical composition lymph also
resembles the blood. Analyses made by Lassaigne of the lymph obtained
from a cow demonstrated that it contains, in 1000 parts, water, 964;
fibrin, 0.9 ; albumen, 28.0 ; fiitty matter, 0.4 ; inorganic salts, 6.7.
The corpuscular elements of the lymph, known as lymph-corpuscles
or leucocytes, are found floating in the lymph-plasma. When examined
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