DISEASE OF OSSEOUS TISSUE IN TIIE HORSE. 
580 
their extreme softness, lost by maceration. The coffin 
bones, also, of all the feet, had the same spongy character. 
The weight of the bones was very much diminished, as 
well as their density. In many instances they were so soft, 
that they could easily be cut with a knife. T he ribs also 
would break by the application of the slightest force. 
I have not yet compared the specific gravity of the 
diseased with that of normal bone, for the difference in 
weight is so marked. Taking the diseased lower jaw in one 
hand, and a healthy one of the same original dimensions in 
the other, the difference in weight is so evident that no one 
w T ould think it necessary to submit them to the test of 
weighing to ascertain it. Nevertheless, I must confess, that 
if the relative difference was exactly ascertained, it would be 
more satisfactory, and particularly to those who have not the 
opportunity of examining the specimens. An idea of their 
density may be obtained by referring to Fig. 4. 
As has been before stated, both maxillary bones belonged 
to animals of the same age, and would be of the same size as 
near as possible, were it not for the diseased condition of one of 
them. Now, although the diseased jaw, from the widening 
of the Haversian canals, is so very much larger than the 
other, it nevertheless is only about two thirds its weight. 
It may be satisfactory to add, that the drawings of the two 
jaws were made by the aid of the camera lucida at exactly 
the same distances, so that their relative proportions are 
perfectly accurate. 
In the heading of this article I have alluded to the 
softening of the bones; this, however, constitutes but one of 
the peculiar changes they had undergone, and would not 
assist in obtaining a knowledge of the other structural 
alterations. Thus it has been explained that in some of the 
long bones, for instance, the femur which I have spoken of, 
the articular cartilage at one of its ends, and the bone like¬ 
wise upon which it rested, had undergone quite a different 
change from that which had taken place at its other ex¬ 
tremity. For example, the cartilage which encrusts the 
condyles was much thinner than natural, and of a dark, 
slate colour in some places, but altogether lost in others, 
the bone beneath it being very soft, and almost black from 
congestion of its vessels and effusion of blood into its 
lamellae. The head of the femur, on the other hand, pre¬ 
sented quite another pathological condition. The articular 
cartilage was here pale in colour, and in some places ap¬ 
proaching a yellowish hue, and when pressed upon it felt 
soft and velvety. Examined more minutely, it was found to 
