112 DR, E, KLEIN, 
IV 
The mucous membrane covering the concha or turbinal bone 
differs in structure from the one hitherto described in the follow- 
ing points :—As is shown in fig. 1 beginning from a, 7.e. imme- 
diately after passing the region of the accessory of Jacobson’s 
organ, the mucous membrane as a whole becomes thicker, owing 
to their being contained in it a continuous layer of serous 
glands. Its thickness diameter amounts here to about 0°25 
mm. But the epithelium becomes thinner (see at a, in fig. 1), 
being now composed of a superficial layer of short columnar 
cells without cilia, and a single deep layer of small polyhedral or 
conical cells. From a to 4, in fig. 1, the epithelium retains the 
character just described ; its thickness is between about 0-016 
and 0°024 as against 0°056, the thickness of the stratified 
columnar ciliated epithelium downwards froma. In the prepara- 
tion from which fig. 1 was taken the epithelium altered its 
character at 2 ; from here over c to d, the epithelium is stratified 
pavement epithelium, consisting of a superficial stratum corneum 
like that of the epidermis, and a deep stratum Malpighii, con- 
sisting of two or three layers of polyhedral cells. Indications 
of minute papille are met with here. The whole thickness of 
this stratified pavement epithelium is between 0-016 and 0-024; 
the superficial stratum corneum is about 0:008 mm. thick. 
Where the stratified columnar epithelium joins the stratified 
pavement epithelium it is seen that, just as in other similar 
regions, the superficial cells of the former become suddenly 
shorter and are continued on the pavement epithelium as the 
superficial layer of scales. 
But not in all places does the stratified pavement epithelium 
commence at 4; in some places the columnar non-ciliated epi- 
thelium may be followed up to ¢, being, however, in one or two 
places interrupted by short islands of stratified pavement epithe- 
lium ; beyond ¢, z. e. up to d, the epithelium is always stratified 
pavement epithelium. 
Near the epithelium the tissue of the mucous membrane con- 
tains a plexus of large veins, chiefly running longitudinally, and 
the membrane is in many places infiltrated with lymph-corpuscles. 
The thickness of the mucous membrane at about J and ¢ varies 
between 0°14 and 0°18 mm.; between ¢ and d its thickness is 
0:14 to 0°3 mm. From a to d the mucous membrane includes 
a continuous layer of serous glands; they are here short tubes, 
generally branched and more or less convoluted. Their duct is 
also very wavy, and it passes in a very oblique or almost horizontal 
direction towards the surface, where it opens with a wide mouth, 
into which the surface epithelium is continued for a short dis- 
