DISEASE OF OSSEOUS TISSUE IN THE HORSE. 
577 
brought the subject before the Pathological Society, and, at 
the same time, exhibited some microscopic specimens of the 
disease, and also drawings illustrative of the morbid changes 
the bony tissue had undergone. An animated discussion 
took place, but nothing was elicited to throw any light upon 
the cause which had given rise to the disease, and which, 
apparently, was one that none of the members present was 
familiar with. 
As Dr. Harley has kindly allowed me the use both of the 
drawings and description of the microscopical examination 
of a portion of the ramus of the lower jaw, and of the head 
of the femur, I have availed myself of the opportunity 
thus afforded me, of giving them a place here ; and as the 
drawings were made immediately under his superintendence, 
their correctness is thus vouched for. The descriptive 
matter, also, which he has kindly supplied me with, will 
prove a great acquisition in elucidating the pathology of this 
singular affection. (See annexed plates) 
Fig. 1 represents a longitudinal section of a portion of the lower jaw; 
highly magnified. 
a. Osseous tissue reduced to a fibrous network. 
b. Haversian canals greatly dilated. 
c. Indistinct lacuna. 
d. Gelatinous substance in the Haversian canals. 
Fig. II, represents a similar magnified view of the tissue of a portion of 
the end of the long bones—transverse section. 
a. Haversian canals. 
b . Diseased cavities filled with fat-corpuscles and granular 
matter. 
The following letter will fully explain, in Dr. Harley^s 
own terms, the pathological condition of the specimens. 
• * 
77, Harley Street, W.; 
21 st March , 1860. 
Dear Sir, —The horse’s bones which I examined for you presented two 
well-marked varieties of morbid change; one of which was most charac¬ 
teristically seen in the bones of the head, the other in the long bones of the 
extremities. 
1st, As regards those of the head.—The disease, although it affected all 
the bones, was most advanced in the lower jaw ; I shall therefore limit my 
remarks to a description of it. The bone was considerably hypertrophied 
in its transverse diameter, the periosteum was readily detached, the osseous 
tissue was of a pink colour, and, on pressure, a quantity of blood oozed from 
its surface, as if from a sponge. The osseous tissue was elastic to the 
touch, and so soft that it could, with facility, be cut with a knife. The 
surface of the section had a somewhat fleshy appearance, but, to the nail, 
it conveyed rather the impression of cartilage. 
