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180 THIRD PERIOD—MODERN TIMES
and those of the second dentition from food and drink, must be declared
entirely false. In fact, by opening both jaws of a stillborn fetus, one
may find, on each side of each jaw, the incisors, the canine, and three
molars, partly mucous and partly osseous, and already sufficiently
large and entirely surrounded by their alveoli. Then removing, with a
skilful hand, the incisors and the canines, there may be observed a very
thin partition only just ossified; and if this be removed with equal care,
an equal number of incisors and canines, almost mucous and very much
smaller, appear, which, enclosed in special alveoli behind the first, would
exactly correspond in position each with its congener, if in both jaws
the canine were not resting for the greater part on the next incisor so as
almost to hide it."
As to the molars (by which name also the bicuspids are here meant),
Eustachius says that he found but three on each side, and no trace what-
ever of the others. Nevertheless, he considers it quite probable that the
germs of the latter should also exist in the fetus, although so small as to
escape observation. He gives many ingenious reasons in support of his
mode of thinking, and comes to the general conclusion, that not only
the temporary teeth but also the permanent ones have, all of them, their
origin during fetal life; a false conclusion simply because too general,
and which shows once more how, in biological science, one runs great
risk of falling into error whenever one tries to draw too free deductions
from observed phenomena.
The researches of Fallopius and Eustachius confirm and complete each
other. These two eminent anatomists, who gave great glory to Italy
by their immortal discoveries and works, were the first to shed a brilliant
light upon the development of the teeth, and thus opened up the way to
all subsequent research on odontogeny.
In settling the period in which the formation of the teeth begins,
Fallopius was still more successful than Eustachius. His patient investi-
gations showed him that the development of the teeth commences partly
in the uterus and partly after birth, which is perfectly true, as was made
clear by later embryological researches. Fallopius found in each fetal
In this he agrees perfectly with his contemporary,
jaw twelve teeth. ^
Eustachius, who, as we have seen a short while ago, found in fetusus,
only just born, the incisors, the canines, and three molars for each side of
each jaw. Eustachius, however, observed in the fetus the germs of the
permanent incisors and canines as well, a thing not noted by Fallopius.
It is not to be wondered at that some discrepancy should exist between
' In utno JuoJociin clcntcs jornuintitr in malts, rt t(jtiJi'tn in ni
tiones anatoniic;e, Venetiis, 1562, p. ^9.
