ARTICULAR CARTILAGE. 
161 
was converted into a solid mass, susceptible of taking 
the highest polish. This view of the subject cor- 
responds precisely with a practice adopted by French 
polishers, who are occasionally obliged to fill up the 
pores, or canals, in many of the hard woods, such as 
rosewood and mahogany, before they can bring the 
polish to any perfection. I must now allude to a point 
which, for many years, has been the subject of dispute 
among anatomists, namely, whether the synovial 
membrane is continued over the surface of articular 
cartilage. If a joint from a very young animal be 
examined before it has been used, the surface of the 
cartilage will be found covered with synovial membrane, 
having an epithelium of that variety known as the 
tessellated ; within a short period, however, after the 
joint has been used, the epithelium disappears, and, 
subsequently, the synovial membrane itself. This view 
of the subject is the one generally entertained ; but 
Mr. Toynbee is of opinion that the membrane is not 
unfrequently present upon the cartilage, although its 
epithelial coating may have disappeared. In making 
the preparations described in the Histological Catalogue, 
many hundred sections were taken from the cartilages 
of the four great classes of animals ; all were examined 
with reference to this point, and I have satisfied myself 
that the membrane is rarely, if ever, continued over the 
cartilages of the long bones of the adult. In the 
patella, and other sesamoid bones, the synovial mem- 
brane, as shown by Mr. Toynbee, may occasionally be 
M 
