OSTEOICIA.
The arrangement of abnormal ossifications has puzzled more than one pathologist. Excluding exostosis and hyperostosis (mere local and general hypertrophies) SVC propos-e to examine here all varieties
Adventitious bone forms (a) as an infiltra tion of natural tissues ; as the callus of fractured cartilage ; (c) as an osteophyte ; (d) as an ostema ; (e) as an osteoid ; (f ) as an in filtration of new products.
(a) In the natural tissues. Articular carti lages ossify in some situations with advance of life, as for instance, in the cranium ; the ma terial uniting eroded articular surfaces ossifies ; ossification of the costal and laryngeal carti lages (perhaps more common in phthisis, in proportion to the age at death, than in other maladies) is affected by calcareous deposition in the cartilage cells and inter-cell substance, and by generation of new bone lacume. Carti lage morbidly ossified, as that naturally ossi fied, yields glutin and not chondrin. The anterior vertebral ligament is sometimes os sified in tubercular caries of the spine. We have seen the tendons of the legs infiltrated with ossiform substance. The fibrous cap sules of the spleen and kidneys are sometimes thus affected, and aponeuroses and fascice are often, and the elastic ligamentum nuchm, more rarely, in a similar predicament. — Cellidar membrane. The subnzucous tissue of the gall bladder; the subserous of the pleura (as a specimen before us proves) ; the subretinal ; the intra-nzuscular ; the parenchymatous (ofthe liver); are all the occasional seats of bone de velopment. Muscle has disappeared and been replaced by bone in some rare cases ; the crys talline lens has been similarly destroyed.
(b) Fractured cartilage is healed not by cartilaginous, but by fibrous or osseous, sub stance.
(c) Under the name of osteophyte (Lobstein) we include ossiform products generated ex ternally to, but under the influence of, some one of the natural bones. Formed from extra-osseous exudation an osteophyte may be separated from its parent bone, without necessary injut y of this (herein differing from true exostosis); and is produced indepen dently of, or in connection with, other pre existing new formations.
Osteophytes assume shapes singular and various, yet in some measure characteristic of their origin. Thus they are flat, and more or less broad in nodes ; narrow, triangular, and semicircular in cephalhmmatorna ; folia ceous, (jig. 97), stalaectiform, cauliflower, (U. C. Alas.), or stellate, when plunging into soft growths ; styloid when passing in front of a vertebra destroyed by caries ; sacciform, when investing a soft growth from bone ; warty-, when found about gouty joints ; mem braniform and lace-like in the cranium of pregnant women.
The flat osteophyte (sometimes separable from the subjacent bone) is best exemplified in nodes, though it forms under the influence of common periostitis or adjoining inflam mation, as beautifully shown by the ribs of an old sufferer from empyema, preserved in the University College Museum. If a node be carefully examined, it will be found in part to consist of hypertrophy with rarefaction of the superficial stratum of the original bone ; and in part of ossified subperiosteal exudation. The canaliculi in the latter run at right angles with the axis of the bone,— proving absolutely the existence of a separate centre of ossification : the fact is exemplified on a large scale, init. 97. And it is further illus trated by a portion of carious lower jaw-bone (now before us), separated frora the face of a dipper of Congreve matches, labouring under the singular disease peculiar to workers with phosphorus. On the inner surface of the ramus of the bone (kindly lent to us by Mr. Quain, whose patient the man was *,) appears a flattish osteophyte, partly fibrillar, partly porous and pumice-stone like, of dark .greyish colour, and easily separable at the edge from the maxillary surface : elsewhere are friable earthy-looking particles.