Page 562 - My FlipBook

572 DENTAL EMBRYOLOGY AND HISTOLOGY.

The ossein mentioned above is the calco-globulin of Mr. Rainey. It
is evident that the basis-substance left after decalcifying bone has changed
its nature, and no longer presents the
characteristics of the intercellular sub-
stance in which the lime salts were de-
posited.
The intercellular substance is com-
posed of protoplasm. In life this con-
tains, besides the albuminoids, a living
principle which permits it to modify its
Ibrm and perform functions. Just M'hat
this principle is we have never, by chem-
istry, been able to determine, for by the
Appeuiuceot MitiiY lelt iitei He a citi- i,cp\,f flip rp-nrpnt whioli WP pmnlov to
citionb\H(l Osseous, L imcii e oblong "^'^^ 'J^ ^'^^ iLdgcni wiucn w e employ lO
br uched I one 1 icun t and tauaiicuii demonstrate its molccular constituency
between tueui. , , ,. . . . , N
we destroy the livnig prniciple, and
have left only the material substance which held the active principle in
bounds. Chemical analysis shows protoplasm to be composed of pro-
teids, in which are held in suspension carbohydrates and fats. These
substances are undoubtedly formed from protoplasm by the action of
the living matter of the cell. We also find in different parts of the
body several varieties of substances derived from the above-mentioned
— gelatin, mucin, etc.
constituents of protoplasm
Under the direction of the vital principle found in living protoplasm
—viz. cells—the lime salts are deposited in forms peculiar to each
tissue. Lime salts, however, may crystallize trifhouf the body, but the
form of the structure in the body depends upon the superintendency of
specialized cells. Tubular bone or dentine is deposited by odontoblasts,
and calcospherules of bone by osteoblasts. These cells do not exert
any other influence upon the depositing structure than that of shaping
it accordmg to certain prescribed and prearranged forms. They are, in
fact, but the moulds which shape the accumulating mass. Where lime
salts are deposited in albumen or any other gelatinous material there
appears no definite form other than that naturally assumed by the
particular lime salt when undergoing crystallization.
Renal calculi are in all probability formed by the deposition of lime
salt in a matrix of mucus, for similar calculi can be formed artificially
outside the body. " The chemical sid)stances to be employed in the pro-
duction of the artificial calculi," says Mr. Rainey, " are a soluble com-
pound of lime and carbonate of potash or soda dissolved in separate
portions of water, and some viscid vegetable or animal substance, such
as gum or albumen, mixed with each of these solutions. The mechani-
cal conditions required to act in conjunction with the chemical means are
the presence of such a quantity of the viscid material in each solution as
will be sufficient to make two solutions, when mixed together, of about
tlu! same density as that of the nascent carbonate of lime, and a state of
perfect rest in the fluid in which the decomposition is going on, so that
the newly-formed com])ound may be interfered with as little as possible
in its subsidence to the sides and bottom of the vessel. This will
require two or three weeks or longei", according to the size and com-