Under certain, as yet unknown, conditions, the lime-salts in a soft basis are, by dint of a revulsive metamorphosis, set free so as to incrust and penetrate the said basis, - in a word, effect its ossification.

Such bases are the fibroid textures and blastemata occurring in the form of independent tumors, of membranous expansions, or of irregular masses lodged and entangled within various parenchymata. They may be the product of inflammation (exudation), or merely of an anomalous act of nutrition. The blastema may moreover be extravasate-fibrin, or spontaneous fibrin-coagulate within the vascular apparatus. Such bases are fibrous tumors, fibroid hardened exudates upon normal and anomalous serous membranes, within parenchymata, in the cutis as scar-texture, on the heart's valves, in muscles, in the heart's walls. Such, again, are the central and the peripherous fibrinous deposits in extravasates, after entering upon a fibroid transformation, hypertrophous thickenings of serous membranes and of the tunicas albuginese. Such are, in fine, the Pacchionic bodies, the different fibrin coagula in the heart's cavities

(so-called vegetations), the stratiform deposits within arteries, and the soft matrix of the phlebolite in veins. To sum up, therefore - all the so-termed ossifications of serous membranes, of the thyroid gland, of the heart's valves, of fleshy muscle, of arteries, and of veins.

Even the fibroid fabric which enters into the composition of malignant growths, for example of cancers in soft parenchymata, now and then ossifies into a bony skeleton, or shell-like framework. This is, however, not to be confounded with the thorn-like, stellate and scaly stroma of true bone-texture, accompanying numerous heterologous growths as developed in and upon the bones.

The ossification offers little or no analogy with normal bone, and its development. The bone-earth enters in a molecular form, accumulating, for the most part irregularly, in the soft basis, until the latter is converted into compact bone. The bone-earth is capable of being withdrawn by acids, with restoration of the soft basis. It has sometimes acquired the aspect of a stratiform deposit. Many a wide-spreading ossification, - of the arteries for example, - is concurrent with excessive fat-production in its vicinity.

4. Crete/Action

Finally, fluid blastemata are also liable to ossification. The process is perfectly identical with that which takes place in the fibroid blastemata just enumerated. It is in like manner conditional upon a metamorphosis of the fluid blastema, by virtue of which, the incorporated lime-earths being set free, predominate. Morphologically speaking, the blastema displays the development of free or of celled molecules (granule-cells). It is always accompanied by fat in a molecular form, and by cholesterine crystals. The ossification manifests itself as a lardaceous chalky pulp, as a cement-like and friable, ultimately, as a compact calculus-like growth.

The blastemata entering into this process are either originally fluid, or else originally solid, and subsequently liquefied (croupous fibrin).

These blastemata are either exudates external to the vascular system, or deposits internal to the latter, for instance, accumulated layers within the arteries, the basis of vein-stones in the veins, or coagula smaller or greater in extent (vegetations).

To this series belong the cretefactions of fibrinous, albuminous exudates, of pus, of tubercle, of atheroma in arteries, of vegetations on the heart's valves, of coagula in the veins. Just like ossification, crete-faction presents various grades from the aforesaid progressive pulp-like thickening, to the cement-like, and at length the compact, calculous concretion.

A very peculiar kind of ossification is represented in the cell-incrustations, which have their physiological analogues in the pineal concretions. They appear in a variety of shapes in the vascular plexuses, especially in the turbid, chalky, speedily condensing moisture of the cysts of the choroid plexus, as also in sarcomata and cancers, more especially within the brain. The cells both as primary and as parent-cells, together with their contents, fill with lime-salts, now in a molecular shape, now in that of concentrical layers.