DISEASE OF OSSEOUS TISSUE IN THE HORSE. 
579 
state; for instance, the ulceration of the articular surfaces, 
•which seemed to be altogether confined to the cartilages of 
w v x 
incrustation, was found on their removal to affect the bone 
beneath ; and the loss of structure, however small it might 
be in the cartilage, extended more or less deeply into the 
bone ; the size of the cavity increasing with its depth. This 
fact, I think, proves beyond disputation, that the loss of the 
cartilage depended primarily upon the diseased condition of 
the bone, and that the general thinning of the articular car¬ 
tilages arose from the same cause. Scarcely an articulation 
of the whole body was free from this £< worm-eaten” condition 
of both the bone and cartilage. This state of things is well 
shown by Fig. 3, which represents the inferior extremity of 
the femur, a, and also the patella, £, the ulcerations being in 
both bones marked c. 
It was found likewise, in cleaning the bones after mace¬ 
ration, that, from their extreme softness, great care was 
necessary to prevent the different processes from being 
detached, and the application of the slightest force to a 
portion of ligament or tendon, that was not sufficiently 
separated by decomposition, would be certain to effect their 
removal. 
The external surfaces also of the bones, as contrasted 
with those in a normal condition, had a very singular 
aspect, especially in the flat and irregular-shaped bones. 
The ends* of the long bones were similarly affected, but the 
shafts of most of them deviated but little in external appear¬ 
ance from a healthy state. A transverse section, however, of 
the middle of the shaft showed very distinctly that the 
osseous laminae surrounding the Haversian canals were very 
much thinner than natural, thus necessarily leading to a con¬ 
siderable enlargement of the latter. In the first-named, how¬ 
ever, and particularly in the flat bones, instead of the surface 
being smooth and dense, it had a character not very unlike that 
of fine sponge. The foramina for the passage of the blood¬ 
vessels, and more especially those belonging to the periosteal 
membrane, were much dilated, thus giving the bone a kind of 
honeycomb appearance. This condition, with its accom¬ 
panying increase of size of the bone, is well depicted in 
Fig. 4, which represents two lower jaws, the one diseased, a 3 
the other healthy, b . For the sake of greater contrast, both 
of the jaws from which the drawings were taken were selected 
from animals of the same age. 
The vertebrte and ribs had undergone the same structural 
change, but in a less degree. The spinous processes of the 
former, and the inferior extremities of the latter, were, from 
