ARTICULAR CARTILAGE. 
149 
epithelium, and subsequently the synovial membrane 
itself disappears from all parts subjected to friction, 
although, as Mr. Toynbee remarks, it is sometimes 
persistent on the patella. In all my observations on 
the synovial membrane, and in the sections made for 
description in the Histological Catalogue, which include 
specimens taken from a large number of animals of 
each of the four great classes, I have never found it 
very far in advance of the vessels. 
FIG. 117 . 
A C 
B D 
Vessels of synovial membrane and articular cartilage : a, glenoid cavity of 
human foetus, b, looped vessels of the synovial membrane, c, vertical 
section of radius of human foetus, d, vessels of foetal articular cartilage 
running in canals. 
