Treatise Upon the Genesis and Development of the Dental Follicles to the Epoch of the Eruption of the Teeth. [Volume: 2, Issue: 12, July, 1861, pp. 642-651]

GENESIS AND DEVELOPMENT OF THE DENTAL FOLLICLES. 643
without completely dissolving them. This chemical reaction, in addition
to the physical characters which they exhibit, demonstrates sufficiently
that they are constituted by the phosphate of lime, already combined with
the azoted matter, which is unfavorable to their dissolution in hydrochloric
acid.
These calcareous grains are found, however, in the body of the bulbtissue during the whole period of its existence. In man they are found
disposed at irregular intervals through the whole length of the radicular
part of the bulb; there are some here and there in the coronal part,
generally nearer to its surface than to its centre. They are irregularly
spherical, or ovoid and mammillated at their surface.
This curious production of calcareous masses, which we have found in
the dental pulp of ruminants and rodents, appears to be owing to an exaggeration of the nutritive movement, with a considerable afflux of calcareous materials, which, being more than sufficient for the dental formation, one part is disposed in the body of the bulb in amorphous masses.
This explanation is the more probable, as in conjunction with the existence of these calcareous masses there are deposits of hematoidine, either
amorphous and infiltrated, or crystallized in tufts and needles, (pl. v., fig., f.) This new circumstance can also be explained by an exaggeration
of the nutritive movement and a very considerable sanguineous afflux.
These two phenomena are often presented to our observation, and appear,
if not always, at least very frequently, in the period when the work of
dentification is in full vigor.
Having exhibited the structure of the bulb in the various periods of its
existence, we may now examine the office which it fills in the production
of the teeth.
~ 2. Origin and development of the ivory.-PRELIMINARY-OF THE
PRECISE PLACE AND TIME OF THE APPEARANCE OF THE DENTINE.-In the
examination of a series of microscopic preparations, showing the follicular
apparatus at the different periods of its evolution, there occurs a moment
when the attention of the observer is arrested by the presence of a new
part, which is less transparent than the others, and occupies the summit
of the bulb of certain determined follicles. The attention is arrested
especially by the circumstance that, instead of being clear and transparent, the summits of these bulbs exhibit a blackish tint, darker than
those of the neighboring bulbs, and are themselves bounded by a very narrow, clear line, owing to a particular phenomenon of refraction of the
light. An attentive examination of this dark part, and the dissection of
the follicles where it is found, will show that it is formed by the ivory, and
that it constitutes the first cap of dentine which appears in each follicle.
In examining the constituent parts of the latter from the base to the apex,
the bulb is seen to be successively surmounted by one or two caps of dentine, according to the species of tooth; the cap adheres intimately to the