Wounds of cartilage are not reunited by means of cartilaginous substance, nor is this substance regenerated when destroyed. Nevertheless new growths of cartilage-texture are both frequent and voluminous. The structure of these growths or tumors was first ascertained, with the aid of the microscope, by Johannes Muller, who applied to them the term enchondroma. These excepted, not a single new growth, whether designated as cartilage-like, fibro-cartilage-like, or as cartilaginescence, chondroid, fibro-chondroid, has more than a seeming analogy with true cartilage texture.

Enchondroma repeats all the special physiological textures of cartilage. It occurs both as hyaline, genuine, as fibro-cartilage, and as reticular cartilage, imitating the articular investments, the laryngeal cartilages, and the septum narium on the one side, and the synchondroses of the vertebrae, the cartilages of the external ear, the epiglottis, etc, on the other.

Ordinarily, and especially in the enchondroma of soft parts, all these forms are often found in juxtaposition. The pure hyaline cartilage is, however, the least common, the intercellular substance displaying, for the most part, a fibrillation similar to that in the cartilages of the ribs.

The enchondroma forms spherical, or nearly spherical tumors, with an even, smooth, or else, which is more usual, a mammillated surface. Internally it either presents a continuous hyaline mass, or else, corresponding with its mammillated exterior, a lobulated structure, an aggregate of denser, hyaline knobs or spheres, either held together by a black-contoured, rough, inelastic fibre texture, resembling the intercellular fibrillation, or else imbedded in a loose texture imitating the fibre-layer of reticular cartilage.

Enchondroma chiefly occurs in bones, especially in the phalanges of the fingers and toes, in the sternum, in the ribs, more rarely in other bones, such as the long cylindrical bones, the ilium, the skull-bones. It is also met with in the mammary gland, in the parotis, in the testicle. We have ourselves seen it in the subcutaneous areolar tissue, and on several occasions in the lungs.

In magnitude, enchondroma varies from that of a tumor only just cognizable to that of a child's head, and beyond it. In bone, enchondroma exhibits two varieties, namely, enchondroma with and enchondroma without bony sheath. This osseous capsule is bone, whose texture has become distended and inflated by the enchondroma in the progress of its upward development. In this process it has, for the most part, increased in substance, so that the capsule far exceeds, in this respect, the original bone. Where the sheath ruptures at an early period, the enchondroma is devoid of bony investment. The capsular case of the enchondroma is unessential, and is common to many other heterologous growths developed out of the depth of bone, and more especially out of a medullary cavity. Many of the so-termed cases of spina ventosa of older observers, were probably of the nature of enchondroma.

Enchondroma is benign, provided it does not enter into any specific, infectious metamorphosis, and only undergoes ichorous destruction from irritation. A peculiar predisposition to its formation does, however, exist, as shown by its occurring numerously in one individual (phalanges, ribs, etc.) It affects young persons more especially, although we have known examples of enchondromata first becoming developed at an advanced period of life. Here, however, they are usually concurrent with exostoses and bulky osteophyte forms. Echondroma generally imitates the permanent cartilages; with exceptions, however, - for it ossifies.

Not only have we seen in all enchondromata incipient ossification, but our museum contains specimens, for the most part, if not thoroughly ossified.

Ossified enchondroma is sometimes a white, extraordinarily dense, ivory-like, sometimes a yellowish-white, likewise very dense, although uncommonly brittle, bony substance, deviating in various degrees and various ways from the texture of normal bone. This difference of habit corresponds to a different process of ossification, and to a different elementary texture.

In the first place, we miss the laminated structure of true bone. The medullary canaliculi are present, the bone-corpuscles large, spherical, irregularly grouped, wanting in radiations.

In the next place, and this refers to the second form of bony substance adverted to, the process of ossification recedes still further from the normal. It resembles rather a process of involution, a wearing out of the cartilage, and, like the texture itself, it has its analogies in ossification of the larnyx, and above all, of the cartilages of the ribs. The intercellular substance of the hyaline enchondroma becomes dull, granulated, sallow, lardaceous, and fibred. The cells are centrally transformed into spherical bone-corpuscles without radii, or else the entire large cell-cavities are simultaneously, if not previously, filled with bone-earth. They are interspersed without order, the last mentioned forming comprehensive spherical or oval masses, which, with transmitted light, appear black, and have a diameter of 1/15th of a millimetre. The lamellated structure is wanting. Medullary canals are wanting, or rudiments only of their structure are seen in the scattered grouping of the cartilage-cells.

Enchondroma commonly occurs in a simple form. We have, however, encountered it in the shape of little millet or hempseed-sized tubercula, interspersed through medullary carcinoma of the testicle, an occurrence allied to the frequent entering of true bone into the composition of cancers.