AND NERVES OF THE TONGUE OF THE FROG AND TOAD. 
141 
Instead of sulphuric ether we may employ chloroform, muriatic ether, nitric ether, 
camphor, sulphuret of carbon, naphtha, alcohol, and various other volatile bodies. 
In some cases it will be found more advantageous to examine only a small portion 
of the tongue, which may be done by removing a small piece of the membrane with 
scissors, and interposing it between two slips of glass ; this applies more particularly 
to those animals whose tongues are opake and not elastic. 
Burdach has mentioned another method of examining the dead tongue by dipping 
it into a dilute solution of caustic potash, and then interposing it between the plates 
of the compressorium. As an auxiliary means, I may mention that by the application 
of a dilute solution of potash (about twenty parts water to one of liquor potassse) we 
may also render the living tongue much more transparent. Another means of 
preparation is to keep the animal for several days after death, when the maceration 
of the organ in its own moisture, and the partial state of putrefaction, cause the de- 
tachment of the epithelial scales and the uncovering of the subjacent parts. Each 
of these means will be found to have, in certain cases, its peculiar advantage, and we 
cannot vary and multiply them too much, as in each case we view nature under a 
different aspect. As I have described on a former occasion* the principal phenomena 
connected with circulation in this organ, I will examine now those parts of the tongue 
which have reference to its sensorial functions of taste and of touch. The nerves which 
possess these powers are distributed and supported by the tegumentary membranes 
of the two sides of the tongue, our attention will therefore be directed to the various 
tissues of which these two membranes consist. 
Vlbratile Cilia and Rugae . — The first parts which engage our attention, exclu- 
sively of the mucus on the surface, are the vibratile cilia of the tongue. The most 
active ciliary movement exists at the borders of the tongue. When a minute por- 
tion of the membrane is removed, anywhere near the edges and anterior extremity, 
we generally observe a most active movement at the borders of the fragment, and 
over its surface we find numerous channels running obliquely outwards and forwards, 
evidently corresponding to those rugae we meet with on the human tongue in a 
similar situation. The ciliary filaments seen down these furrows meet at an obtuse 
angle, and exhibit a constant undulating movement transmitted downwards from one 
extremity to the other. Any small body coming into this channel is generally pro- 
pelled quickly in one direction. Occasionally a succession of blood-particles are 
seen running down this channel which might easily be mistaken for blood circulating 
within a capillary. The appearance of the blood-particles viewed with a power of 
400 diameters while beaten about by the ciliary filaments is sometimes very curious. 
The form of the vesicle is seen to vary in the most singular manner, sometimes 
dilated, sometimes compressed longitudinally or transversely, like a bladder partly 
filled with water when beaten about with rods. When the fragment has been freshly 
divided, a general tremor is observed at first, which arises from the irritation of the 
* Phil. Mag. vol. xxix. 
