524 
M. H. REYNOLDS. 
the dorsal and superior cervical arteries have their origin 
near the median line and constantly approach the surface. 
The vertebral is easily located and remembered, because after 
passing beneath the transverse process of seventh cervical 
vertebras (which has no vertebral foramen) it simply follows 
the vertebral foramina of the next five cervical transverse 
processes, and anastomoses with the retrograde branch of 
the occipital. Its only importance in this connection lies in 
its superior and external branches to the muscles we have 
been studying. 
The lymphatic vessels call for some attention in this dis¬ 
cussion, because of the special part they play in distributing 
certain pyogenic bacteria, notably the streptococci. In ex¬ 
ternal portions of the body, they are arranged in two primary 
sets, superficial and deep. The superficial again being 
divided into two networks, one of ver}^ fine meshes in super¬ 
ficial layer of the dermis; the other includes larger vessels 
and is placed quite beneath the skin. The ultimate origin of 
these vessels is still a matter of dispute, but all agree in 
tracing them back to lymphatic capillaries or rootlets, 
described by Klein as situated in epithelial tissue—Von 
Recklinghausen says in serous membrane. Even those 
observers who agree on connective tissue, disagree on other 
points, for Virchow says in plasmatic cells, while Ranvier 
says those cells are not cells at all, but radiating, connected 
spaces. Regardless of this ultimate-origin question, it is that 
delicate plexus in the superficial derma that interests us now, 
and which will be made use of in discussing modes of bac¬ 
terial entrance. The larger and deeper lymphatic vessels are 
also divided into two classes, a superficial, ramifying in the 
tissues of the deeper aponeuroses, and a deep, following the 
larger veins, and lodged in the vasculo-nervous intermiscular 
sheaths. Every vessel traverses, one or more lymphatic 
glands before emptying into the thoracic duct or right lym¬ 
phatic vein. Those of the head, neck and front legs are all 
directed toward the prepectoral, at the chest entrance. Most 
of the large vessels in the region also pass through a smaller 
collection of glands, which lie beneath the mastoido-humeralis 
