206 CONTRIBUTIONS TO ZOOLOGICAL PATHOLOGY. 
far as I have observed) in all the other true ginglymoid joints of 
the skeleton. In regard to the first of these statements, I have 
found them in the feline, canine, ruminating, and pachydermatous 
animals generally, and also in the larger species of our domesti- 
cated gallinaceous birds that have come within my power for dis- 
section ; and in all of these animals, also, the appearances were 
similar in situation and structure. In reference to the second, I 
have found them especially in the hock and elbow joints, as also 
in the fetlock and pastern joints. In my examinations of these 
sulci, I confined myself chiefly to those seen in the hock joint: in 
as far as this joint is of a large size, the articular cartilage is com- 
paratively thick and well developed, and the sulci are larger and 
more distinct than in the other ginglymoid joints. It is also a 
joint where the general anatomist will find many facilities for ex- 
amining the general arrangement and structure of the cartilaginous 
plates that form the cartilage of incrustation to the different joints 
of the skeleton. 
In its general physical properties this cartilage is elastic in the 
highest degree ; of a white colour, with a bluish, yellowish, or in 
the lower animals of a slight pinky tinge, more or less transpa- 
rent, and easily cut with a knife. When dried, it becomes of a 
brownish yellow colour, transparent and hard ; and in those joints 
where the sulci are found, the surface of the osseous paste that 
forms their base shines through the groove, so as to give rise to a 
polished or ivory appearance. In thickness, the cartilage varies 
much, even in the same joint, being thickest on a convex part 
and towards the centre, and thinnest in a concave part and towards 
the circumference. Its free surface is smooth and covered by the 
delicate synovial membrane of the joint, from which it cannot be 
separated ; and the attached surface, irregular and nodulated, is 
equally intimate in its union with that part of the bone on which 
it rests, the one being dove-tailed into the other. 
In its anatomical arrangement it consists of a series of plates or 
lamellse, placed vertically on the surface of the articular extremity 
of the bone, some of which are shallower than the others, so as 
to form cavities of insertion and attachment to the projecting 
nodules of the osseous surface. 
In their microscopic structure, these plates are found to consist 
of a basement intercellular substance, in the meshes of which are 
deposited, at irregular distances, the linear nucleated cartilage cor- 
puscles, surrounded by a nearly homogeneous matrix or hyaline 
substance — the fluid substance of cartilage. These cartilage cells 
measure from tfW 1° °f an inch. The central nuclei are, for 
the most part, small. In the interior of the cartilages of incrusta- 
tion, the external cells assume more or less of a linear direction, 
