222 DR. E, KLEIN. 
maxilla, in the shape of a thin lamella of bone, extending 
along the convex surface of Jacobson’s cartilage. It soon 
becomes very conspicuous, covering not only the convex 
surface of the cartilage, but gradually embracing the greater 
part of the circumference of the organ of Jacobson, as shown 
in figs. 1 and 2 of my paper in the January number of this 
Journal. In the posterior portion of the organ of Jacobson, 
viz. where the cartilage of Jacobson is wanting, as has been 
just mentioned, the former, 7. e. the organ of Jacobson, is 
entirely enclosed in the osseous substance of the nasal crista, 
as is shown in fig. 7 of the present memoir. 
In figs. 1,2, and 3, z. e. in the anterior portion of the nasal 
organ, the lower nasal furrow (4) is lined with columnar 
ciliated epithelium, like that of the septum; it has been 
minutely described in my former memoir, ard need not, 
therefore, be referred to here any further. The very bottom 
of the furrow, however, is lined with stratified pavement 
epithelium, of which the superficial layers consist of sqamous 
epithelial cells, each possessing a flattened nucleus. In the 
preparations from which the above figures are taken these 
superficial layers are more or less loosely attached to the 
rest of the epithelium, hence appear as if desquamating. 
The stratified epithelium, as a whole, is stained very much 
deeper in these preparations than the columnar epithelium, 
and is therefore very conspicuous in the drawings. 
Such is the state of the epithelium at the bottom of the 
furrow in the front part (figs. 1, 2, and 3). But, going 
further back, we find that this part of the furrow, viz. the one 
lined with stratified pavement epithelium changes its posi- 
tion, inasmuch as it does not now occupy the very bottom of 
the furrow, but gradually extends inwards and upwards 
towards the concave surface of the Jacobson’s cartilage. An 
inspection of figs. 4 and 5 will make this easily understood. 
At 12 in these figures the changed position of the part 
covered with stratified pavement epithelium is well seen. 
Now, this pit, viz. marked 12, is the commencement of 
the organ or tube of Jacobson, or, more correctly speaking, 
the anterior opening of this latter into the nasal furrow; we 
shall call it the mouth of Jacobson’s organ. Its diameter is 
about 0°05 mm., not including the lining epithelium, whose 
thickness is about 0°057 mm. 
A little way further back (see fig. 5) we meet already 
with the well-formed tube of Jacobson, and we still recog- 
nise here the stratified pavement epithelium, occupying, as 
must be expected from what has been said before, the upper 
part of the tube; the lower part is lined with columnar 
