302 
mann (in Stricker’s ‘ Handbuch,’ Heft iv), in direct connec- 
tion with which the forked taste-cells are placed. Exner 
describes a perfectly clear and simple connection of the 
*‘ epithelial’’-cells with this nervous network, and figures 
their continuity. Max Schultze had described these cells as 
passing to the deeper lying connective tissue layer, to which 
they appeared connected by a three-cornered enlargement. 
This network, now pointed out by Exner, appears to consist 
of a protoplasmic mass, with numerous meshes in it contain- 
ing nuclei, which nuclei are like those of the ‘ smelling-cells.”* 
With very thin sections, prepared in osmic acid, and teazed 
out, it was possible to observe the direct connection of the 
cells with this network. Max Schultze describes a network 
in the olfactory mucous membrane of the Plagiostomi, which 
agrees very closely with this, and he also appears to have 
seen, though not fully to have described and figured, 
Exner’s network in the frog. 
The olfactory nerve forms a plexus in the connective tissue 
beneath Exner’s network, and the branches from this plexus 
pass straight up directly into the overlying network, such 
a branch occupying the space between two of the .nucleus- 
containing meshes. Here the branches gradually lose their 
characteristic fibrillar aspect, and pass by degrees into the 
protoplasmic matter of Exner’s meshwork, thus completing ° 
the connection of the nerve with the cells. This connection 
is fully illustrated in nature-true drawings in the paper, and 
rests on observation, not on hypothesis. 
Exner doubts whether the fine fibrillar structure often to 
be seen in branches of the olfactory nerve, when they 
have been torn so as to present a jagged end, is a living or 
a post-mortems tructure. Max Schultze has regarded these 
very fine fibrille, with their intermittent swellings, as con- 
tinuous with the identical fine fibrille, one of which comes 
from each “ smelling-cell’’ (so also with the rods of the retina). 
The course of the fine fibril coming from each “ smelling- 
cell” appears to be quite impossible to follow; it may, and 
probably does, end in the protoplasmic substance of Exner’s 
meshwork, but is so fine that it would be apparently im- 
possible to trace it further. Two folding plates illustrate Dr. 
Exner’s paper. 
a 
