226 DR. E. KLEIN. 
the wall is greatest in an upward and downward vertical 
direction. | Scattered lymph-corpuscles and more or less 
well-defined accumulations of them, 7¢.¢e. true lymph-follicles, 
are met with in the upper wall of the duct close to the 
epithelium (see figs. 7 aud 8). 
Henle! mentions in the lower portion of the human 
naso-lachrymal ducts the richness of its wall in lymphatic 
tissue and in a cavernous tissue, this latter being a con- 
tinuation of the cavernous tissue of the lower nasal concha. 
In fig. 8 [have given an accurate representation of the wall 
of the naso- lachrymal duct, and ‘it will be here ‘seen that 
the. stratified columnar epithelium, with the vascular in- 
traepithelial vesicles or cavities, the subepithelial fibrous 
layer; and. the subepithelial, venous plexus are well marked. 
I cannot ascertain whether the superficial cells bear cilia 
or not. In my last paper I have given several reasons why 
I think that.they are ciliated but I have not been able to get 
further in this matter. Henle? maintains that in man the epi- 
thelium lining tlie duct is simple columnar ciliated epithelium 
as against R. “Maier, 3 who describes it as stratified columnar 
non-ciliated epithelium. 
The thickness of the epithelium is here about 0-068, the thickness of 
the sub-epithelial fibrous layer is 0°012—0°016 mm., and the diameter of 
the veins of the sub-epithelial plexus is between 0-028 and 0°04 mm, 
The rest of the wall of the duct, in fig. 8, shows an 
artery ascending towards the internal surface and connected 
at its.capillary end with a lymph-follicle. 
The lymph-follicle, which I described and figured in fig. 1 
of my first memoir, is not in reality a. solitary follicle but 
is one of a patch of lymph-follicles extending in a longitu- 
dinal direction, and therefore seen in the figure in trans- 
verse section. Besides these follicles, I find one large patch 
of lymph-follicles on each side of, and close to the epithe- 
lium lining the lateral wall of the lower nasal furrow a 
little behind the region of the organ of Jacobson. The long 
diameter of this patch, ¢.e. anterio-posteriorly, is about 
3°4 mm., the thickness diameter, z.e. from side to side is 
about 0°45 mm. The individual follicles of the patch are 
spherical, closely placed side by side, and in some places 
their outlines are indistinct; the diameter of the largest 
follicles is about 0°3—0°45 mm. 
Both the upper and lower wall of the duct contains a 
1 ¢ Kingeweidelehre,’ ii, p. 713. 
oe Fa pe 
3 ‘Ueber d. Bau d. Thranenorgane,’ Freiburg, 1859, p. 31. 
