568 DR. E. KLEIN. 
section appears in all preparations more or less oval, but is more 
flattened from side to side anterior to the organ of Jacobson. 
As regards the size, it appears greatest in about the region of the 
mouth of the organ of Jacobson; anteriorly and posteriorly of 
this it appears to decrease in size. 
The following are the measurements of its lumen only, ante- 
rior to a point shown in fig. 1: 
The short transverse diameter ; : : . 0135 mm. 
The long ¥ ‘ : : : «) ee os 
At a point represented in fig. 1: 
The short transverse diameter F é : . 01385 mm. 
The long PS a : : , « OF8752, 
A little behind this point, but before the mouth of Jacobson’s 
organ is reached : 
The short transverse diameter varies between . . 0°56 and 0°68 mm. 
The long transverse diameter between. ; « 24S ai Si 
In the region of the middle of the organ of Jacobson the naso- 
lachrymal duct becomes again smaller, as is shown by the following 
numbers : 
The short transverse diameter varies between . . 038 and 06 mm. 
The long transverse diameter between ; « LOL Ba eee 
As regards the structure of the naso-lachrymal duct it is 
everywhere the same: 
1. The stratified columnar epithelium lining the lumen is of the 
same nature as that described of the guinea-pig; the thickness 
of the epithelium varies between 0°048 and 0:068 mm. 
2. This epithelium is placed, just as was the case in the guinea- 
pig, on a thin subepithelial layer infiltrated with lymph-corpus- 
cles. In many places there are large lymph-follicles present in 
the wall of the naso-lachrymal duct; these lymph-follicles have 
their seat really in the subepithelial layer, and extend from here 
both into the epithelium and in the outer parts of the wall of the 
duct. Between more or less well-defined lymph-follicles and 
diffuse adenoid tissue infiltrating the subepithelial layer are 
all gradations. The diameter of a medium-sized lymph- 
follicle, such as is shown in fig. 14, amounts to about 0°45 mm. 
The adenoid tissue of these lymph-follicles penetrates into the 
surface epithelium to the extent of the disappearance of this 
latter at these places, just as is the case in other places where 
lymph-follicles reach to the surface, e.g. Peyer’s patches of the 
intestine, tonsils, and pharynx, &c. 
But independent of the lymph-follicles, the adenoid tissue, at 
any: rate the lymph-corpuscles and capillary blood-vessels of the 
