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86 EMBRYOLOGY OF THE DENTAL TISSUES.

Fui. 73. Fig. 74.

Sections of very young- enamel (human), showing the appearance of a fibrous s-tructure : 1, enamel
cells; 2, newly forming enamel; 3, dentin.

of living matter in formed enamel, it is undemonstrable. Klein states
that it is improbable that nucleated protoplasmic masses are contained
in the interstitial substance of the enamel of a fully formed tooth.

CALCIFICATION OF THE CEMEXTUM.
In the year 1858, Magitot, a French histologist, claimed to have
found within the follicle of a developing tooth a special organ for the
development of the cementum. In 18G1 Robin and INIagitot made a
presentation of the same facts. With the exception of these authors,
no other authority has recognized the presence of this special organ ;
while Kolliker, Waldeyer, Herz, and others had formerly denied its
existence. Although there are appearances, in a fully formed follicle,
of a tissue between the calcifying dentin germ and the outer covering
of the sacculus, which might admit of the supposition of the existence
of such an organ, it cannot be traced with certainty. The appearance
may be noted in sections from embryos of the pig and calf. At a later
stage when the crown is further developed there are also to be seen
infoldings of the tissue at the base of the germ which may develop
into a special organ for the formation of the cementum, as stated by
Magitot ; but in teeth more matured, where the cementum has already
commenced its growth, there are no indications of a special organ.
If the developing tooth is examined just after the cementum has
begun to form, its matrix will be found to be made up of masses
looking like scales of a tissue found everywhere on the borderland of
calcification. It is calco-globulin, and has been formed from globules.
At this early stage the calcific material is in the osteoblasts, and is
given from them to the dentin, where a thin layer is forming. The