88 
APPENDIX. 
the human subject. The coverings of the brain, and 
tte ganglions, and peculiarities of the nerves, are an- 
nexed. The organs of sense are an-anged in the or- 
der of tlieir simplicity, beginning with that of touch, 
which is only a villous vascular surface, the villi very 
short, where the impression is to be made through a 
thin cuticle, or in the human finger ; very long w'here 
the covering is thick, as in the hoof of the horse. 
The organ of taste is only a modification of the or- 
gan of touch, and therefore nothing in the organiza- 
tion is different ; but the varieties in structure adapt- 
ing the tongue for different purposes are numerous. 
In many animals it serves the purposes of a hand, 
to bring the food to the mouth, as in many shell- 
fish, the ant, bear, woodpecker, and chameleon. Con- 
nected with the tongue are the fauces, which in many 
animals have peculiarities. In the electric eel, they 
have a very curious carunculated appearance ; but 
they are yet more extraordinary in the camel, which 
has an apparatus to moisten the parts, so as to pre- 
vent the painful sensation of thirst, thus adapting it 
to the sandy deserts which it is destined to inhabit. 
This apparatus consists of a large bag hanging down 
several inches in the fauces, and attached to the 
palate, which tlie animal can at pleasure m.ove up 
and down, and lubricate the fauces. The organ of 
smell is variously constructed, and is more compli- 
cated m many animals than in man, as in the lion 
and sea-cow. The organ of hearing in fish consists 
of three semicircular canals, but is much more com- 
