LYMPHATIC SYSTEM )F SKIN AND MUCOUS MEMBRANES, 401 
situated close to the surface. When examined undera lense 
it will be seen that the network is very dense, and that the 
vessels are either straight or slightly wavy and irregular. 
A few larger vessels with distinct valves may be seen in the 
depth; the direction of the course of the efferent trunks is 
away from the free margin of the lip, in the parts near the 
middle line, straight towards the gums, at the side towards 
the mucous membrane of the angle of the mouth. 
When injecting into the part situated between the cutis 
and mucous membrane of the lip, it will be found that the 
injection material passes much more frequently into the lym- 
phatics of the mucous membrane than into those of the cutis. 
But in every injection into the cutis of the one side of the 
[ip the injection does not readily pass beyond the middle 
line, that is, from one side into the other. Injecting, how- 
ever, the lymphatics of the mucous membrane, no such 
demarcation between the two sides can be observed. 
37. The injection of the buccal mucous membrane and of 
that of the palate and pharynx shows also—these organs 
being examined in the fresh state in the bird’s-eye view—a 
beautiful and dense network of fine lymphatics, the meshes 
being of a more or less uniform polyhedral shape. 
38. In the tongue, however, the aspect of the lymphatics, 
as seen in the bird’s-eye view of the fresh organ with the un- 
aided eye or witha lens, greatly differs from the above organs, 
owing, of course, to the presence of the papilla. On the 
doreal part of the tongue there is found a network of fine 
lymphatics, whose meshes correspond to the papille; they 
are naturally larger for the fungiform than for the filiform 
papillee. 
The lymphatics of the tissue of the papille themselves are 
not visible under these circumstances. 
Owing to the peculiar change of the surface at the margin 
of the tongue, viz. the papillae becoming arranged in more 
or less distinct transverse rows, the shape of the network of 
the lymphatics undergoes a corresponding variation, that is, 
its meshes become elongated in a transverse direction. 
At the margin of the tongue we notice numerous efferent 
vessels passing from the dorsum on to the lower smooth 
surface ; they are more or less parallel with one another. 
At the base of the tongue the arrangement of the lym- 
phatics changes from a uniform network of fine vessels into 
one with elongated meshes. There is an exquisitely by dense 
network of very fine vessels surrounding each circumvallate 
papilla. 
In man and in animals I have always found a plexus of 
