208 CONTRIBUTIONS TO ZOOLOGICAL PATHOLOGY. 
and flocculent, and is bedewed with a small quantity of synovial 
fluid ; and if a very recent joint be carefully opened and then ex- 
posed in an apartment to a freezing atmosphere, and after a few 
hours examined with a powerful glass, the entire surface of the 
sulcus will present the appearance of innumerable, small, and iso- 
lated particles of frozen synovia, suspended like grapes on and 
around minute filamentous tendrils, formed by tufts of the intercel- 
lular substance. When a thin, transverse slice of the margin and 
centre of the sulcus is placed in the field of the microscope, with a 
high power applied, the white, fibrous filaments that form the 
meshes in which the hyaline substance and the nucleated cartilage 
corpuscles are deposited will be found to be comparatively great 
in quantity, resulting from a deficiency in the development of the 
two former constituents. In the pulpy margin, however, they will 
be found more numerous than in the centre ; and they will also 
be found to increase the more we approach the general compact 
surface of the articulation. 
In the greater part of the cavity of the sulcus nothing but fila- 
mentous substance will be found, forming a loose and flocculent 
network over the surface of the bone below. This latter presents 
its usual roughened and papillated surface, for insertion between 
and around the adherent points of the lamellae of the articular car- 
tilage ; but I have never found it changed in its consistency, or 
presenting the porous, worm-eaten appearance, of a carious sur- 
face, which would be found if this solution of continuity in the 
cartilage depended on the existence of a morbid cause. 
T have never found, in the sulcus or around its margins, the 
pavement of tesselated epithelial cells before mentioned, as form- 
ing the superficies of the synovial structure ; but, from what has 
already been mentioned, these could scarcely have been expected 
to be met with. 
From the situation and microscopic structure of these sulci, 
therefore, I am inclined to view them as a normal, and not as a 
morbid structure ; and from these convictions I am also inclined to 
adopt the opinions expressed by Professor Dick, M. J. F. Rigot, 
and Ferguson, that, 
1st, These synovial fossae, which have been mistaken for ulcer- 
ations, are frequently to be found in the articulations of all our 
domestic animals. 
2d, That they seem to be developed more as the animal advances 
in life, and as his labour becomes greater. 
3d, That their appearance is quite different from that presented 
by cartilage when inflamed. 
4th, That, when the articular cartilage will be found diseased, 
there will also be found an altered state of the synovial membrane. 
