100 REPORT—1874. 
deeper part, which is first attenuated and then expanded into a broad flattened 
process, apparently connected with the connective tissue ; the other cell, the proper 
olfactory cell, a thin, fibrous, rod-like body, is moniliform or varicose, connected 
below with the out-runners of a nerve-cell, and in birds and amphibia furnished 
with one or more hair-like processes, which at the free end come directly into contact - 
with odorous particles. Exner in 1872 denied the distinctness of these two forms 
of cells, stating that there are all intermediate forms, and that both forms are con- 
nected with a deep network continuous with filaments of the olfactory nerve. But 
Dr. Newell Martin, in a paper published in the November Number of the ‘ Journal 
of Anatomy and Physiology,’ maintains that the two kinds of cell are distinct, 
though their characters approximate very closely in the instance of the frog. He 
inclines to the belief that, as both forms of cell are so distinct from ordinary epithe- 
lium, they are all olfactory cells. 
The only conclusion which can be drawn from these observations is that in this 
situation the olfactory nerves divide into myriads of small finger-like processes, 
which, exposed on the free surface of the membrane, are actually engaged 1n feeling 
at the odorous particles to inform us of their characters, 
This single instance, so thoroughly proved, would be sufficient to destroy our 
former ideas that nerves are spread out under basement membranes and never pene- 
trate an epithelial layer. 
But this is not the only case of the kind. The general relations of the gustatory 
nerves to the epithelial cells of the tongue have been described by Axel Key as 
similar in the fungiform papillz of the frog, and by Schwalbe and Lovén in the 
gustatory cells of the circumvallate and of some of the fungiform papille in men 
and animals. On the protected sides of the circumvallate papille a peculiarity in 
the shape and arrangement of the epithelial cells produces a series of taste-cones, 
the central cells of which are furnished with hair-like prolongations similar to those 
of the olfactory cells. 3 
In the otolith-sacs and the ampulle of the semicircular canals of the ear, the 
nerve-filaments, having lost their‘white substance, become connected with peculiar 
auditory cells and end in hair-like processes between the epithelial cells. In the 
cochlea, too, notwithstanding the complication of the examination produced by the 
rods of Corti, there is reason to believe that the cells supporting hairs which pro- 
ject beyond the epithelial surface are connected with the primitive nerye-fibrils of 
the plexus below. 
Of the recorded instances in which nerves pass through basement membranes to 
get into direct contact or continuity with the superjacent epithelial cells, none is 
so striking as that of the salivary and other glands, if there be the least ground for 
the remarkably detailed observations and suggestions of Pfliiger. They are of so 
much importance and interest in connexion with the whole process of secretion, 
that I offer no excuse for directing your attention to them, even though it may be 
proved that the act of secretion is not attended with such marvellous and extensive 
changes of structure as Pfliiger supposes. Up to a certain point his observations 
may he easily and abundantly contirmed ; beyond that there is much greater diffi- 
culty; but this Meeting offers one of the most favourable opportunities for extending 
our knowledge by bringing different observers into easy communication with each 
other, and enabling each to help the rest by stating the means by which he had 
overcome what seemed at first to be insuperable difficulties in the progress of an 
investigation. 
Pfliiger calls attention to the very variable characters of the alveoli, the secreting 
cells, and the excretory ducts of the salivary glands. These parts, which were 
believed to have very determinate sizes and characters, he declares to differ very 
greatly in different parts of the same gland. The alveoli, occupied by what we 
understand as secreting or glandular epithelial cells, and the excretory duets, lined 
hy columnar epithelium, he thinks he can prove to be but different stages of deve- 
lopment of the same structures, produced on the ends of the myriad nervous fila- 
ments supplied to these glands. 
On this view glandular epithelial cells must be regarded as special organs of 
termination of nerve-fibrils, like the auditory cells, touch-corpuscles, olfactory cells, 
muscular fibre-cells, and the like—the relation between such structures and the 
