346 



DISEASES OF THE FEET. 



the inflammatory action ; its vessels are injected, its surface 

 presenting a red streaky appearance; it becomes slightly, but 







■^•r 



O'- 







Fig. 63. Fig. 64. 



Fig. 63 shows the gradual ejection of the tissues of the cartilage at the ulcerated 

 spots. In the centre of the hollow the superficial parts of the cartilage have disap- 

 peared, and the deeper parts are undergoing degeneration, becoming irregular, 

 shrivelled, losing their walls, and discharging their contents. — (After Redfern.) 



Fig. 64. — Vertical section of cartilage, showing the notches produced by burst- 

 ing of the cells, and the fibrous and granular mass on the free surface. — (Redfern.) 



This figiure very fairly illustrates the change in the navicular cartilage at an 

 early stage of its conversion into a finely granular calcareous substance. 



never much thickened; in very 

 chronic cases its free surface 

 becomes involved in the gene- 

 ral adhesive process, and united 

 to the tendon and bone. 



The changes in the cartilage 

 are the same as when the carti- 

 laG^e of incrustation is inflamed 

 in an articulation (see Chapter 

 XI.) ; it is either removed from 

 the surface of the bone by ulcera- 

 tion, or converted into fibrous 

 tissue or a calcareous material. 



The supposition that the sur- 

 FiG. 65 shows the superficial cells of faccof this cartilage is naturally 



the cartilage enlarged, and passing into a j ■> i • a. 



granular and fibrotsmass on the surface. COVCrcd by a membrane IS not 



borne out by microscopic inves- 

 tigation ; the supposed membrane being nothing more than 

 the cartilage corpuscles, which are flattened upon the free sur- 



