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THE SIXTEENTH CENTURY IM

the ()bser\ arions ot these two eminent anatomists. The researches of
which we are speaking are sufficiently cleHcate and difficult; and even much
more recent authors are far from agreeing perfecth , as far as regards the
period, in which the development of the teeth begins. Serres, in his Es.uu
siir ranatotnie ct la physiologir Jrs dents (Paris, 1H17), sustains the view
that in the fetus he has observed the germs of all the teeth, both temporary
and permanent, while Joseph Linderer {Handbiicli der Za/nilirilhindf,
Berlin, 1842) says that, although he has followed the preparative method
indicated by Serres, he could never discover in the fetus the germs of
all the teeth. Perhaps, he adds, the time when the development of the
reeth begins varies considerabh' in individuals, just as we remark differ-
ences in the time of eruption.
In Chapter XVII of his book, Eustachius speaks of the process of
formation of the teeth, which he studied in abortive fetuses, in stillborn
children, in children a few months old, and also in kids.
On dissecting a fetal jaw, there may be found on each side, as we have
already seen, the incisors, the canines, and three molars, still soft and
imperfect, separated from one another by very thin osseous partitions.
Each of these teeth is enclosed within a follicle or little bag of a gra\ ish
white color, rather more mucous and glutinous than membranous, and
in form somewhat like the pod of a vegetable, with the only difference
that it shows an opening at one of the extremities, from which the tooth
somewhat protrudes, as if it were germinating. The more recent and
softer the tooth, the more its follicle has a mucous appearance and differs
from the nature of membranes. As it does not adhere to the under-
hing tooth, it is easy to separate them. As to the tooth, it is at that
period of its development partly osseous and partly mucous, since that
part which later on projects from the gum soon becomes transformed
into a white thin and concave scale, which gives the idea of one of the
little cells of a honeycomb. This scale is harder and more conspicuous
in the incisors, since these, at this stage, are better formed; the canines
are less advanced in development, and the molars still less; and among
these latter, those are less developed which are more distant from the
canines. The deeper part of the tooth consists of a mucous and tenacious
substance, harder, however, than the substance of the follicle, and of a
whitish color with a tendency to dark red, translucent, and somewhat
brilliant.
Thus, says Eustachius, the teeth present themselves in a human fetus;
but he who cannot obtain a human fetus may observe the same things
in a kid.
Although the author does not express himself very explicitly', he seems
to consider the follicle of the tooth substaniialh- identical with its liga-
ment. "This is at first mucous, but afterward, becoming more consistent,