Bauhaus-Universität Weimar

The Cyclopaedia of Anatomy and Physiology, vol. 4: Pla [corr.: Ple] - Wri
Todd, Robert Bentley
cortical, undergo softening and rarefaction, 
and are gradually spread out into a globular 
sac. New bony matter is also thrown out, help¬ 
ing to complete the capsule, which is, even with 
this assistance, commonly imperfect. When 
developed in bones of very spongy texture, 
perforation may, according to Müller, occur, 
instead of expansion ; we believe that, in at 
least some such cases, the growth originates 
in the sub-periosteal cellular membrane. In 
this latter variety the form is less regularly 
spheroidal than in the other ; but the texture 
is the same in both. 
The progress of enchondroma is slow ; its 
effects fundamentally are purely mechanical. 
Adhesion of the skin only occurs as an acci¬ 
dental effect of inflammation : rupture of that 
membrane only from excessive distension ; 
the resulting ulcer may discharge abundantly, 
and inflammation arise from this cause, as from 
external injuries, but not apparently from in¬ 
trinsic spontaneous changes. 
Enchondroma of the bones, like every other 
affection of those organs attended with en¬ 
largement, has been described under the 
names osteosarcoma, osteosteatoma, and spina 
ventosa—terms devoid of definite significa¬ 
tion. Scarpa speaks of it as “malignant 
exostosis,” a double misnomer—for its course 
differs essentially, as has been seen, from 
that of cancerous maladies, and it does not 
necessarily spring -from bone. 
Colloid cancer might possibly be confounded 
with enchondroma. We:have already alluded 
to a rude mark of distinction between the 
two products ; further,-colloid cancer rarely 
(never so far as our experience goes) occurs 
in bone, the chosen site of enchondroma ; the 
effects of the two products on adjoining 
tissues are essentially different — enchon¬ 
droma never infiltrates structures, colloid fre¬ 
quently does ; colloid never contains patches 
of bone, enchondroma does so commonly ; 
colloid is of protein basis, enchondroma yields 
chondrin, or (rarely) glutin. 
Certain sarcomata of the maxillæ have 
much outward resemblance to enchondroma ; 
but they contain spherical cells with granules 
and fusiform corpuscles, and are besides of 
albuminous composition. 
§ 3. OSTEOMA. 
The arrangement of abnormal ossifications 
has puzzled more than one pathologist. 
Excluding exostosis and hyperostosis (mere 
local and general hypertrophies) we propose 
to examine here all varieties of bone-produc¬ 
tion in unnatural sites. We adopt this course, 
in order to avoid recurrence to the subject un¬ 
der the head of Pseudo Tissues, being aware 
that ossiform masses, having the generic attri¬ 
butes of Growths, ought alone to figure in the 
present place. Hypertrophy and new produc¬ 
tion of bone, as in the venereal node, are fre¬ 
quently associated ; and adventitious bone 
(whether springing from a new cartilaginous 
matrix or not) is very rarely perfect micro¬ 
scopically, perhaps never so chemically : two 
fundamental propositions. 
Adventitious bone forms (a) as an infiltra¬ 
tion of natural tissues ; (b) as the callus of 
fractured ^cartilage ; (c) as an osteophyte ; (d) 
as an ostema ; (e) as an osteoid ; {/) 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 lacunæ. 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 nuchæ, more 
rarely, in a similar predicament. — Cellular 
membrane. The submucous tissue of the gall¬ 
bladder; the subserous of the pleura (as a 
specimen before us proves) ; the subretinal ; 
the intra-muscular ; the parenchymatous (of the 
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¬ 
(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 maybe 
separated from its parent bone, without 
necessary injury 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 cephalhæmatoma ; folia- 
ceous, {fig. 97), stalactiform, cauliflower, 
Fig. 97. 
Foliaceous osteophyte of the clavicle; the foliæ (6) 
running at right angles with the accis of the bone (a\ 
(U. a Mus.) 
(U. C. Mus.), or stellate, when plunging into 
soft growths ; styloid when passing in front


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