202 NOTES OF THE EXAMINATION OF 
substance, of a peculiar white aspect, too gritty and friable for true bone, and 
having a dark confused appearance under the microscope, with no definite 
structure ; but after maceration in dilute hydrochloric acid presenting both to 
the naked eye, and under the microscope, the characters of cartilage. As a 
general rule, this calcified cartilage was present in greatest amount where the 
cartilage was thickest. Fig. 2 exhibits part of a section made perpendicular 
to the surface of one of the prominences of the exostosis; a is the cartilage 
covering the surface, and is upwards of a line in thickness ; the calcified cartilage 
b immediately beneath it was very dense, while at e the texture was looser, 
Fic. 1 is a lateral view of the exostosis: at @ a piece of the tumour has been broken off, and the loose structure 
of the interior shows itself. 
Fic. 2 exhibits part of a section through one of the prominences of the tumour: a is the superficial cartilage ; 
c isa portion of cartilage situated deeply, and surrounded on all sides by dense calcified cartilage, b and 
d; e is the deepest part of the calcified cartilage, of looser texture than the more superficial parts. 
Fic. 3 shows a section of a portion of the tumour at the line of junction of the calcified cartilage and the 
cancellous structure of the interior; the earthy matter has been removed by dilute hydrochloric acid : 
a is the cartilage with its cells changed by the process of calcification; b c is true bone (containing 
lacunae) lining the excavations in the calcified cartilage; d is part of a spiculum of the cancellous 
structure: e and / are spaces formerly occupied by medullary substance. 
but even there, at a depth of five-eighths of an inch below the surface, cartilage 
cells showed themselves after maceration in acid. 
The microscopical appearances of the superficial cartilage presented nothing 
very remarkable ; the cells were larger than they are found in human articular 
cartilage, and many of them were of rather complex structure ; they were much 
elongated at the free surface, where, indeed, it was difficult to distinguish them 
from the contiguous part of the investing cellular tissue ; while in the deeper 
part of the cartilage they were more or less elongated in a direction perpendi- 
cular to the surface of calcification (a figure was shown representing one of 
these deeper cells). The matrix was homogeneous or faintly granular. The 
matrix of the calcified cartilage as seen after maceration in acid, was more 
