THE VASCULAR SYSTEM. 151 
penis, two or three iliac glands are near the origin of the 
femoral artery, and a few small lumbar glands lie in the 
lumbar region of the abdominal cavity. 
All parts of the body have communication with the 
lymphatic vessels, which for the most part are so small as 
to be invisible unless injected, when they are easily recog- 
nized by their beaded appearance caused by the numerous 
valves within them. There are two systems of vessels in 
the head and extremities—the superficial and the deep. The 
former accompany mainly the superficial veins, and the lat- 
ter follow the deep veins. On the outer aspect of the tho- 
racic limb just beneath the skin two vessels are present, 
which flow into the cervical glands. They carry the lymph 
from the ball of the foot and the skin of the foot and 
forearm. One or two deep lymph-vessels are found ac- 
companying the brachial vein and artery, which convey the 
lymph from the bones and muscles of the arm to the axil- 
lary gland. 
In the pelvic limb two or three superficial vessels are 
present transmitting the lymph from the foot to the pop- 
liteal gland, whence two vessels proceed to the deep lym- 
phatic system. The lymph from the bones and muscles of 
the leg reaches the iliac glands through two or three deep 
vessels lying near the femoral vein and artery. The in- 
guinal glands receive most of the lymph from the skin of 
the leg. 
The lymph from the superficial parts of the head flows 
largely into the submaxillary glands, while that from the 
brain, tongue, esophagus, and larynx empties into the 
laryngeal glands. 
The lymph of the right forelimb, right side of the neck 
and head, and right side of the thoracic wall is received by 
the right tracheal trunk. The left tracheal trunk receives 
the lymph from the left side of the head, neck and thoracic 
