THE NASAL REGION IN EUTAENIA. 397 
nuclei, but after a stay in Miiller’s Fluid the nucleus is found adjacent 
to the wall of the now perfectly spherical cell. The opening of the 
gland takes place at an indentation on the surface of the membrane. 
The following account of the structure of the Organ of Jacobson 
based partly on my preparations, was contributed by Prof. Wright 
to the Zoologischer Anzeiger (No. 144), and will serve to explain his 
figures (Nos. 8, 9, 10): 
““The Roof.—Immediately within the osseous capsule which the 
Vomer forms for Jacobson’s Organ lies a somewhat scanty mucosa 
which is largely occupied by olfactory nerve-bundles: it is more 
richly pigmented than the corresponding layer in the nasal cavity, its 
blood-vessels are of larger calibre, and it is destitute of Bowman’s 
Glands. Most of the elements of the mucosa are continued inwards 
towards the lumen of Jacobson’s Organ between its cellular columns 
which are thus isolated from each other by pigmentary connective- 
tissue and capillary vessels. Very few of the olfactory nerve-fibres 
appear to run in the partitions thus formed, the bundles entering the 
outer ends of the cellular columns almost entirely. The capillaries 
arrived at the deep surface of the Neuro-epithelium form there a 
plexus, the polygonal meshes of which are occupied by the inner 
ends of the cellular columns. This plexus obviously corresponds to 
that on which the Neuro-epithelium in the nasal cavity rests ; but 
there is no intervening basement membrane, for a reason which will 
be presently apparent. The Neuwro-epithelium (inside the plexus) is 
only 33 u high, and the greater part of this belongs to the superficial 
stratum (as defined above), while only one or two layers of cells cor- 
responding to the nuclear are to be detected. These latter cells, 
however, differ in form, according as they stand opposite a node or a 
mesh in the capillary plexus; in the former case they are shorter, 
and their deep processes are bent in such a manner as to pass around 
the vessel, in the latter case they are more fusiform and they retain 
this shape for three or four layers while passing through the mesh 
in the corresponding cellular column. With the exception of these 
spindle-shaped cells which form their inner ends, the cellular columns 
are formed entirely of cells, completely resembling those of the nu- 
clear stratum in olfactory epithelium of the nasal cavity ; i. e., they 
possess rounded nuclei (6—7 “ X 5 ~) surrounded with very scanty 
protoplasm prolonged into processes at either end. The highest 
columns measure about 300 vy. 
The Floor.—The following structures‘may be traced from roof to 
floor. 
(1) The layer of ordinary cylindrical epithelium cells which .are 
now Only 15 u high and bear short cilia ; between the bases of these 
are wedged small rounded cells forming rarely more than one layer ; 
these rest on 
