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X. Minute structure of the Papillce and Nerves of the Tongue of the Frog and Toad. 
By Augustus Waller, M.D. Communicated hy Richard Owen, Esq.^ F.R.S., 8^c. 
Received Feb. 26, — Read April 13, 1848. 
The attention of physiologists was first directed by me to the peculiar advantages 
possessed by the tongue of the living frog and other similar animals for micro- 
scopic investigation, in the year 1839. The extreme elasticity and transparency of 
this organ induced me to submit it to the microscope, principally with a view of 
examining the muscles during contraction. I communicated these experiments to 
M. Donne, who has mentioned my claim of priority in his Cours de Microscopic, 
p. 108, and they were first made public at the Societe Philomatique, Aug. 17, 1839*. 
It will be unnecessary in a communication addressed to the Royal Society, to occupy 
the time of that learned body by recapitulating what is already known respecting the 
organ of taste. I shall therefore proceed at once to describe the results of my further 
researches on this organ, by which I have been enabled to determine the peculiar 
structure of the papillae, and the ultimate termination of the nerves within them. 
In conclusion, I will point out the deductions which necessarily ensue with regard 
to the distinct nature of the functions of these organs in the act of taste. 
Tongue of the Frog. 
In this we find the same component parts as in the tongue of man. The principal 
points of difference are its smaller size, and the manner in which it is placed in the 
mouth. In other respects it presents the greatest analogy with that of the human 
subject. Its frame-work is composed of two muscles, the hyoglossus and the genio- 
glossus. The hyoglossus arises from the inferior border of the body of hyoid bone 
and ascends to its superior border, the fibres diverging ; afterwards it reflects back- 
wards in the throat, the fibres forming a fan-like expansion. The genioglossus is a 
small, thick, triangular muscle, inserted by its base to the centre of the lower maxil- 
lary. The summit terminates near the inner third of the tongue in a tendinous ex- 
tremity. These two muscles unite at an acute angle, and when at rest hang down 
the throat. The form of the tongue differs from that of other animals. The anterior 
extremity is broad, with a notch which divides it into two extremities or tubercles. 
The precise form of the extremity is best seen when compressed between two slips of 
glass. In a state of rest the extremity of the tongue hangs down the throat, where 
it serves as a valve to close the posterior nares in the act of swallowing the air for 
* Minutes of which are to be seen in the Journal de I’lnstitut, p. 316, year 1839. 
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