434 The Submaxillary Gland 
the interalveolar capillary plexus remained completely empty as the 
mass reached only the arterioles running in between them. He con- 
cludes that these facts indicate “the presence in the salivary glands of 
two vascular systems with unequal resistances; a system of diminished 
resistance with capillaries in the walls of the ducts, and the system of 
greater resistance with capillaries in the lymph spaces between the 
alveoli.” The arteries of the salivary glands, according to Kowalewsky, as 
well as the ducts and veins, run in the connective tissue between the 
lobules. They give, in their course, small twigs that divide twice or three 
times and run mostly in recurrent direction in the connective tissue wall 
that surrounds the ducts. Here the arteries pass over into capillaries 
which sink quickly to reach the neighborhood of the epithelium under 
which they form a comparatively thick plexus. The veins from these 
capillaries appear in a more superficial position, change their direction 
so that it is parallel to the surface of the ducts and unite to form larger 
trunks which, at a certain distance from the afferent arteries, terminate 
in the accompanying veins. Small branches are also given off from the 
interlobular arteries which supply the sympathetic gangha situated in 
the interspaces. As the ramification proceeds there is a thinning of the 
connective tissue wall of the salivary ducts and the capillary plexus at 
these points is not so well developed. The arteries and veins accompany 
the interlobular connective tissue until they finally penetrate into the 
interior of the lobules. The intralobular ducts, like those of the extra- 
lobular system, have a capillary plexus derived from the intralobular 
arteries. This empties into the vein that accompanies the duct. The 
intralobular system divides with the ducts until they reach the surface 
of the lobules. Arriving at this point, the terminal arteries are some 
what thicker than capillaries, but in the absence of muscle elements they 
can scarcely be distinguished from them. As soon as the lobular surface 
is reached, the arteries customarily divide into several divergent branches 
which form recurrent arched loops and immediately break up into capil- 
laries around the alveoli. These vessels or vascular arcades, according 
to Kowaiewsky, are already in the lymph spaces and send from their 
concave portion capillary twigs into the interalveolar lymph spaces which 
surround the single alveoli. From these capillary plexuses between the 
alveoli appear numerous short venous radicals which run in the neigh- 
borhood of the salivary tubes and soon terminate in large veins which 
accompany the ducts in their subsequent course. In this short descrip- 
tion Kowalewsky does not trace the exact transition from the arterial 
to the venous system in various parts of the gland, nor does he discuss 
the important relations of the vascular and anatomical units. Moreover, 
