146 
DR. A. WALLER ON THE MINUTE STRUCTURE OF THE PAPILLA 
frequently with an irregular pointed extremity. The rest of the tubes still eontinue 
in close contact, and when they have attained the membrane of the area, end 
abruptly in an irregular manner, some in a point, some club-shaped, some in a spiral 
form, others like small funnels, but most often with a kind of concentric mouth. 
In some papillae the nerve-tubes keep close together until their termination, which 
takes place immediately at the surface of the area at its central point. Their open 
mouths are closely joined, and almost interlaced with one another. In others the 
terminations of the nerve are still more evident, for the tubes are seen expanding 
and crossing over each other so as to supply as equally as possible each of the areas 
enclosed by the capillary loops. 
Nerves of the inferior surface of the tongue. — This surface presents neither conical 
nor fungiform papillae. Its epithelium consists of flat nucleated scales, extremely 
thin. In a portion of this surface removed from the organ and interposed between 
glass, we may detect abundant convolutions of the nerves, similar in every respect 
to those found under the conical papillae ; they are very tortuous, form frequent 
loops, and are reduced to the state of nearly single tubes. 
Mucous follicles. — These are seen over various parts of the upper surface inter- 
spersed among the papillae. Their appearance at the surface is that of an anal 
opening generally closed during life, forming a slightly prominent tumid ring. 
After death, or when the membrane is much distended, the eye penetrates into their 
interior, where an active ciliary motion exists. When the surrounding membrane is 
denuded of its scales, we perceive around the opening two striated muscular fibres, 
forming a curve on each side, and performing the office of a sphincter. The follicle 
forms a bottle-shaped cavity, exactly like the small follicles over the skin of the frog, 
particularly near the anus. It is supplied by a capillary which runs close by it, 
without encircling or spreading over it. The follicular nerve consists of one or two 
tubules, and makes a single or double coil when it reaches the follicle. 
In reeapitulating these observations, we find in the frog an organ of taste similar 
in its general structure to that in man. At the upper surfaee are bodies corre- 
sponding to the conical and fungiform papillee. At the inferior surface the membrane 
is smooth and without anything of the kind. We may therefore conclude that the 
upper surface has the faculty of taste and of touch, and that the under surface is 
merely tactile as in our own species. The fungiform papillee consist of a membranous 
vesicle or utricule, containing coils of capillaries, numerous nerves, and muscular 
fibres, and probably lymphatics. Where do the nervous elements which these bodies 
contain extend themselves? We invariably find that they terminate at a part of the 
utricule where the membrane is so transparent that we may almost doubt whether 
they are surrounded at all by a membrane. This is the area which I term the gusta- 
tory or neuro-vascular, where the action of the nervous radicels is performed, which 
being conveyed to the brain excites an impression of taste. Another element ob- 
served in this area is the existence of numerous and intricate coils of capillary vessels 
