344 



DISEASES OF THE FEET. 



in another, to the formation of large carious-looking cavities ; 

 exposing the vascular interior of the bone (see No. 3, Fig. 62), 



PlO. 62 represents external appearance of inferior articulating surfaces 

 of four navicular bones. 



1. Apparently healthy bone ; externally it presents no appearance of 

 disease. It is carefully selected as typical of an apparently sound bone, its 

 cartilage of incrustation being intact, and the tendon perfectly healthy. 

 The animal from which it was taken had been lame from navicular disease 

 before its death. Its internal appearance is represented by No. 3 in the 

 preceding illustration. 



2. Calcification of the articular cartilage. The calcareous spots indi- 

 cated by the dark dots ; interior of this bone much opened up. 



3. Caries of articular surface. 



4. Adhesion of tendon to the exposed cancelli of the bone. 



with gradual removal of the bone, its texture at same time 

 becoming friable, until at last it may become fractured by some 



