696 HISTORY, &C. OF AN OSSIFYING ENCHONDROMA. 
part was so hard that no doubt could be entertained as to its con- 
taining more or less perfect ossific matter. 
By microscopic examination, the tissues entering into the forma- 
tion of the tumour were ascertained to be, firstly, fat and fibrous 
tissue (white and yellow), which structures in no way differed 
from those met with in healthy parts ; secondly, cartilage ; thirdly, 
bone. 
A thin perpendicular section of the cartilage with some of the 
adjoining fibrous tissue, being placed under a microscope, exhibited 
the true organisation of cartilage; “nucleated cells disseminated 
in a solid mass or matrix.” It is remarkable that, as the cartilage 
corpuscles approached the surface, they were found to become very 
much flattened, and apparently to degenerate into, or at any rate 
to become very intimately blended with, the adjacent fibrous tissue 
and fat. The intercorpuscular substance or matrix appeared in 
some situations homogeneous and transparent, in others granular ; 
and at wide intervals a few delicate fibres might be seen winding 
their course between the cells. 
A transverse section of the bone, seen under the microscope 
with transmitted light, exhibited somewhat imperfectly the ordi- 
nary structure of osseous tissue. 
With a view to determine how the bone was formed, Mr. 
Gamgee, after having been shewn by Dr. Sharpey a specimen of 
ossifying enchondroma from the femur of the human subject, made 
a perpendicular section of the cartilage, including at one extremity 
a very small portion of the partially ossified structure. By care- 
ful microscopic examination, this section was found to exhibit the 
same general characters as those in Dr. Sharpey’s possession. 
The walls of the cells were found to become very indistinct as the 
boundary of ossification was approached ; their nuclei were 
arranged in groups, and earthy deposit, in the form of granules, 
pervaded the matrix. At the confines of the cartilage and bone, 
the earthy deposit could be seen advancing between and around 
the cartilage cells, some of which were only partially enclosed. 
The quantity of ossific matter obtainable in one section being ex- 
tremely small, it did not appear safe to deduce any inference as to 
the mode of transition from mere cartilage, with earthy matter 
impregnating the matrix, to an imperfect appearance of the true 
structure of ordinary bone. 
The precise structure of the tumour having been ascertained, the 
question arose — To what class of tumours did the one in question 
belong ! The conclusion arrived at on this point is, in the author’s 
own words, the following : “ Considering that the tumour above 
described agrees with Muller’s enchondroma in process of ossifica- 
