216 



DISEASES OF THE JOINTS. 



of the ulceration, exhibit any traces of vascularity, and the 

 membrane, which was supposed by Goodsir to be the cause of 

 the ulceration, is regarded as the result of the disease. The 

 formation of this false membrane, which is sometimes on the 

 bone, sometimes on the attached surface of the cartilage, has 

 conveyed the erroneous impression, entertained by some ob- 

 servers, that in one form of destruction of articular cartilages, 

 the destruction is preceded by the formation of vessels in the 

 substance of the cartilage itself. It is quite certain that in 

 nearly all instances of destruction of the articular cartilages, 

 in the lower animals at least, there have been extensive ulcera- 

 tions without the presence of any vascular membrane ; and in 

 one instance that fell under my notice, a false membrane was 



^* li;i>^-"^" '^^^^L':^>■■>^'/^':S.■y:•:.rL■?^^^ 



-»- l;.-:^ 



Fig. 3». 



Fig. 37. 



Fig. 37. — Diseased articular cartilage, showing the enlargement of the cor- 

 puscles, the increase of the nuclei within them, and their escape into the 

 eoftened matrix. — (Redfern.) 



Fig. 38. — Deepest part of a vertical section from the cuneiform surface of 

 the semi-lunar bone, showing the cells, with thickened walls. — (Redfern.) 



found covering the articular surface of the astragalus, the 

 cartilage of which presented no signs of ulceration ; whilst the 

 tibial cartilage of the same joint was ulcerated without being 

 covered by any adventitious membrane. 



The further changes are the bursting of the enlarged cells 

 at the surface of the cartilage, which by this change becomes 

 disintegrated. In some cases, the nuclei which have escaped 

 from the cells become elongated, and incorporated with the 



