Periscope of Medical and General Science in their Relations to Dentistry. [Volume: 2, Issue: 5, December, 1860, pp. 289-304]

PERISCOPE OF MEDICAL AND GENERAL SCIENCE.

289

PERISCOPE OF MEDICAL AND GENERAL SCIENCE IN THEIR
RELATIONS TO DENTISTRY.
BY GEO. J. ZIEGLER, M.D.
* Teeth of Alligators.-The following instructive remarks on this subject
occur in an interesting paper in the New Orleans Med. and Surg. Jour.
for November, by DR. BENNET DOWLER, on comparative anatomy and
physiology, in which he treats more particularly of the Crocodilus Mississippiensis:"The mouth of the alligator, never completely closed against either air
or water, owing to the absence of lips, presents on each side double
curves or gently undulating lines of the jaws, the general bearings of
which rise above the horizon considerably from the tip of the muzzle to
the posterior angles of the mouth.
"The teeth, variable in size and length, are conical or of the canine
type, a portion being somewhat blunt, especially posteriorly, but none
adapted to grinding. They are more formidable in appearance than in
reality, being hollow shells and easily fractured, even by biting hard substances.
"In an animal from ten to twelve feet long, the largest tooth is less
than a quarter or the third of an inch in diameter, while a vast majority
are much smaller. The teeth are inserted into distinct sockets, except
about one-fourth, which enter a trough or gutter, forming the posterior
angles of the mouth.
"Anatomical adaptation, as well as actual observations, show that the
teeth are designed to seize, hold fast, pierce, and kill their prey. Alligators find much difficulty in preparing their prey, when the latter are too
large to pass the unyielding bony strait of the jaws and palate. To facilitate this preparation for deglutition, they bend their heads laterally, so as
to bring the mass within the reach of one of the forelegs, in order to tear
the food to pieces. The limb and claws, however, are feeble aids for this
purpose, being comparatively small. In fact, they appear to be generally
unable to divide solid bodies which are too large to be swallowed whole,
as will more fully appear in the sequel.
" From the curves of the jaws, the variable size, length, and non-opposition of the teeth, and from the position which the teeth of the under
jaw take within the dental arch of the upper, and from the fact that the
under teeth enter into shallow holes, or a kind of sockets, in the soft
parts or alveolar gums of the roof of the mouth, as well as from the
acute, almost needle-pointed shape of the teeth, especially the longer
ones, it is evident that the dental apparatus can have no horizontal motion forward, backward, or laterally, and that they act only perpendicularly to the plane of the jaws, penetrating, but never masticating by
grinding; nor can they divide by incising their food or prey, if solid,
resisting, and coherent. The reader will recollect that, from the days of
Aristotle to the present century, it has been generally asserted that the
upper jaw opens without moving the head. Even Denon (born 1747,
died 1825,) of the French Egyptian Expedition, is quoted as authority
for this anatomical myth, (Voy. i., 185.) St. Hilaire, naturalist to the
same expedition, embarrassed by the classics, (Aristotle, Herodotus, and
VOL. II.-21