ANGEIOLOGY. 103 
but more delicate than that of veins; they have three coats, but the middle, 
as in the veins, is thin, and wants the elastic lamina. 
The lymphatic or conglobate glands are very numerous both in the 
extremities and in the trunk; their size varies from that of a small currant 
to that of an almond; the largest are in the groins and in the roots of the 
lungs. ‘Their form is round, or irregular and lobulated. 
The Lymphatic Vessels of the Lower Hatremities. These are superficial 
and deep. ‘The superficial commence from the toes, rise along the dorsum 
of the foot, and pass up the leg in two divisions, which, however, frequently 
communicate: one, the internal group, passes in front of the inner ankle, 
and keeps parallel and close to the great saphena vein; these branches 
ascend to the groin, and pass through the inferior superficial gland into the 
external iliac gland. The external set of superficial lymphatics ascend 
behind the inner ankle, accompany the external saphena vein to the ham, 
pass through the glands there situated, and join the deep lymphatics of the 
limb. 
The lymphatics of the trunk and viscera are very numerous and exceedingly 
complicated. The absorbents of the small intestines are either lymphatics 
or lacteals; the former arise in the subserous tissue, the latter in the sub- 
mucous tissue and in the villi. The lacteals proceed at once from the intes- 
tine into the mesentery and its glands: they take up the chyle and pour it 
into the thoracic duct. : 
The thoracic duct, great or left, is the common recipient of the absorbents 
not only of the infra-diaphragmatie portion of the body, but also of those 
of the left side of the chest, head, neck, and left arm. It commences by the 
confluence of a variable number of branches, in a common reservoir or 
dilatation called receptaculwm chyli, which is placed to the right and some- 
what behind the aorta, and rising into the neck, arches forwards and down- 
wards, opposite the seventh cervical vertebra, and empties into the angle 
between the left subclavian and jugular veins, protected by a pair of valves 
against regurgitation from these vessels. 
The head, face, and neck are well supphed with lymphatics. Ten, how- 
ever, occur in the cranium, and none have as yet been detected in the brain. 
In the upper extremity, the superficial lymphatics commence from the 
fingers and the back part of the hand, and accompany the subcutaneous 
veins. The deep lymphatics follow the individual blood-vessels, reach the 
axillary glands, and receive various branches. On the left side they accom- 
pany the subclavian vein and join the descending portion of the thoracic 
duct. On the right side, the axillary or subclavian lymphatics, joined by 
the right cervical, form a short trunk about an inch in length, termed the 
right lymphatic duct. This trunk opens into the angle between the right 
subclavian and jugular veins; it is the termination of the lymphatics of the 
right arm, right side of the thorax, and of the head and neck. 
Pl. 136, fig. 14’, superior vena cava; °, azygos vein: *, thoracic duct ; 
*, portion of the pelvic plexus; °, external iliac do.; °, lumbar do. ; *, recep- 
taculum ; *, point of union of the chyliferous vessels of the intestinal canal, 
with the thoracic duct; °°, intercostal lymphatics; “"°, deep lymphatics of 
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