LYMPHATIC SYSTEM OF SKIN AND MUCOUS MEMBRANES, 403 
describe this relation, and I will merely refer the reader to 
Fig. 12. The above irregular outline of the wall of some of 
the lymphatics is due to the lumen of the vessels being in 
open communication with the interfascicular spaces of the 
surrounding tissue. 
41. An important and intimate relation exists between 
the most superficial lymphatics and the epithelium of the 
surface. 
This relation is of the same nature as the one I have shown 
to exist between the epithelium constituting the outer root- 
sheath of the hair-follicles and the surrounding lymphatics, 
viz. a direct passage of wyection material from the lym- 
phatics—both the lymphatic vessels and sinuses as well as 
the interfascicular lymph-spaces—cnto the interstitial or 
cement substance between the epithelial cells. That there 
exists a direct connection between the lymph-spaces of the 
most superficial layer of the mucosa, including the papille, 
and the interstitial cement-substance of the epithelium, can 
be ascertained in every thin section of a well-prepared 
mucous membrane; it will be found, on careful examination, 
that the spaces between the fine connective-tissue bundles 
—some of which correspond, as is shown in injections, to 
lymphatic vessels—are distinctly prolonged into the inter- 
stitial substance of the epithelium. This is still more con- 
spicuous in slight inflammatory conditions, when the lymph- 
spaces are enlarged and the interstitial substance is much 
increased in amount. The branched cells situated in the 
interstitial substance of the epithelium, mentioned on former 
occasions, are also here in connection with the connective- 
tissue cells situated in those lymph-spaces. 
In Fig. 11 is represented a horizontal section through the 
most superficial parts of the mucous membrane of the lip of 
a rabbit, and it is noticed here that the interstitial substance 
of the epithelium, which includes here as well as in many 
other mammals pigment granules and pigmented branched 
cells, contains the injection matter (Berlin blue), and that 
this passes directly into the interfascicular lymph-spaces and 
the most superficial lymphatic vessels. 
The very same condition exists everywhere in the oral 
mucous membrane and pharynx as regards the interstitial 
substance of the stratified epithelium of the free surface and 
the superficial lymphatics—a condition which, I need hardly 
say, is of great physiological importance. This relation can 
be studied in sections of simple uninjected preparations as 
well as in successfully injected specimens, and it is borne 
but by the observation of Toma and Arnold and others as 
