280 CONTRIBUTIONS TO ZOOLOGICAL ANATOMY. 
the centre of each section, but more scattered along the mar- 
gins. In conformation they are of a curved, pyramidal form, the 
base being attached to the investing membrane and the curved 
point directed backwards. In their directions, when viewed late- 
rally, and the tongue of the living animal is kept in the bottom 
of the mouth, they appear to lie flat along the surface, but imbri- 
cated on each other from before backwards, with their apices all 
directed to the epiglottis. 
No sooner, however, is any sapid body or any other stimulus 
applied to the surface, or the lingualis muscle called into action so 
as to shorten and draw back their bases through the medium of 
the investing membrane, than they are immediately elevated. 
When thus seen they appear, in the tongue of the dog and cat, 
arranged in comparatively regular and transverse lines, like the 
teeth of a file, and in that of the ox as so many tenter-hooks for 
collecting the herbage ; and thus, not only will long fibrous matter 
be easily secured, but fluids once introduced into these channels 
can be safely and easily transported into the back of the mouth 
and pharynx during the pendent position of the head. 
In structure they vary much, according to their situation on the 
surface of the organ. Posteriorly, they are of the same structure 
as that of the dermo-mucous membrane from which they are pro- 
duced. Anteriorly, however, the cartilaginous elements are in 
greater abundance, and especially in their apices, which are more 
firm and dense than their bases, and which approach almost to a 
horny or bony hardness. The cuticular layer can be seen passing 
from the general investing membrane upon their bases ; but it be- 
comes entirely lost towards their points, which are formed entirely 
of cartilage. These horn}' or cartilaginous apices, therefore, may 
be viewed as a sheath or hoof to the more sensitive and more vital 
bases ; and thus they will better withstand, like the enamel of the 
teeth, the wearing down effects which constant friction and contact 
with foreign bodies would induce. 
In the dog, and especially in the cat, the apices of these papillae 
are very dense and sharply pointed, as can easily be felt by per- 
mitting the latter animal to rasp the sensitive skin on the back of 
the hand. With such a conformation of parts, therefore, might 
it not be asked, whether or not these numerous, sharp pointed pa- 
pillae could be extensive and fruitful causes for the inoculation of 
the virus of rabies contagiosa by the simple process of licking, and 
without a bite ever having been inflicted*? 
It is not for me, at present, to discuss the nature and pathology 
of this scourge to the brute, and also to the human race ; but it is 
* Vide Youatt on Babies Contagiosa, and Blaine on Diseases of Dogs, 
5 th edit., page 220. 
