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THE ORGAN OF JACOBSON IN THE RABBIT. 567 
fibrils the nerve plexus. I have given an illustration of these 
appearances in fig. 12, and from this it will be seen that in this 
respect the relations appear very similar to those described by Max 
Schultze and others of the olfactory nasal mucous membrane, 
but different from what is maintained by the latest investigator of 
this subject, viz. Cisoff. Both in teased and non-teased specimens 
of vertical and horizontal sections I have convinced myself of the 
continuation of the subepithelial plexus of nerve fibres as plexus 
into the sensory epithelium, and of the intimate apposition of the 
deep process or processes of the sensory cells to the plexus, from 
whose fibrils they could not be distinguished either in aspect or 
position. 
The naso-lachrymal duct in the rabbit, in the whole extent of 
of the organ of Jacobson, is considerably larger than that of the 
guinea-pig. or some distance anterior to the commencement 
of the organ of Jacobson the naso-lachrymal duct is seen on each 
side in the lateral wall of the nasal furrow, inside the cartilage, 
forming the support of this latter between it and the surface 
epithelium. In a section a little way further behind, like that 
shown in fig. 1, the naso-lachrymal duct is seen outside the car- 
tilage plate, mentioned in the introduction as the lower limb of 
the cartilage, forming the support of the superior concha. 
This changed relation between the naso-lachrymal duct and the 
cartilage is not due to any change in position of the naso- 
lachrymal duct, but to the fact that, as mentioned above, there is 
a small cartilage plate present in the most anterior parts which is 
not continued as far as the section represented in fig. 1; and, on 
the other hand, the lower cartilage limb shown in this figure is 
not present yet in sections anterior to the one shown in this same 
figure. 
Behind the section represented in fig. 1, until the disappearance 
of the cartilage in the lower concha (fig. 3) the naso-lachrymal 
duct retains the same position as before, viz. outside the cartilage. 
It is situated just in the angle formed by the lower limb and 
lateral limb of the cartilage forming the support of the lateral 
wall of the nasal furrow. Compare figures 2 and 3. 
Behind the mouth of the organ of Jacobson, the naso-lachry- 
inal ducts are seen at the roots of the plicated part_of the inferior 
concha between its osseous support and the alveolar process of 
the upper maxilla (see fig. 4). 
In the region of the posterior part of the organ of Jacobson 
the naso-lachrymal duct changes slightly its position, inasmuch 
as it descends a little lower down, 7.¢. nearer to the lower nasal 
furrow. 
As regards the shape of the naso-lachrymal duct, its cross 
