JO4 DR. E, KLEIN. 
‘he median wall comprises much the greater half of the wall 
of the organ, extending almost over two thirds of the whole 
circumference. Its thickness is about 0°14 mm.; at the lower 
sulcus it decreases slightly. The most conspicuous feature in this 
is the sensory epithelium ; its thickness is 0°.l mm. What is 
not epithelium, 7.e. outside this latter, is fibrous tissue inti- 
mately connected with the perichondrium, or internal periosteum 
respectively. Numerous small nerve-branches are contained in 
the subepithelial layer, and here they may be followed as oblique 
or longitudinal bundles, ultimately ascending into the sensory 
epithelium. These bundles are derived from large branches, 
which are contained as groups, and in company with blood- 
vessels, in the channels of the plough-shaped upper part of the 
cartilage above mentioned. Most of the nerve-bundles are 
derived from the olfactory nerve, and, like this, are composed 
of non-medullated fibres; but there are a few small bundles 
of the nervous naso-palatinus of Scarpa. Gratiolet+ has very 
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exhaustively treated of the origin and distribution of these nerves. 
As has been mentioned above, the gland alveoli at the lower 
sulcus extend a short distance into the median wall. 
The sensory epithelium extends over the whole of the median 
wall proper, and the greater part of the adjacent sulcus superior 
and inferior. Its structure is this: most superficially it, viz. 
the epithelium as a whole, presents a faint vertical striation, the 
strie being due to thinner or thicker granular-looking columnar 
bodies. These, on careful examination with high powers, prove 
to be either the thicker processes of the deeper cells reaching 
up to the surface, or conical, thin epithelial cells, whose basis 
forms part of the general surface. The conical cells are the 
“ epithelial cells,” and they are smaller and thinner, and their 
nucleus less distinct, than the epithelial cells of the olfactory epi- 
thelium of the nasal cavity. Hach of these epithelial cells appears 
to be possessed of a narrow, oval, transparent nucleus. Below 
the layer of epithelial cells are several layers of spherical, 
comparatively large nuclei, well outlined, and containing 
a delicate reticulum. Hach of these nuclei belongs to a 
spindle-shaped, granular-looking cell, of which one process, the 
outer one, is broad, but thinner than an epithelial cell, and 
extends as one of the above striz between the “ epithelial 
cells,” up to the free surface, while the inner is very delicate, 
and directed towards the depth. These spindle-shaped cells will 
be spoken of as the “ sensory cells ;” the amount of all substance 
around the nucleus is always appreciably larger than in the 
olfactory cells”? of the olfactory region, with which they are 
evidently analogous. 
1 Loe. cit., p. 23 e¢ passim. 
