222 ■ DISEASES OF THE JOINTS. 



mental here than in the healing of ordinary wounds, many 

 actions which take place in these textures proceed very slowly, 

 and therefore are in greater danger of being interfered with 

 in their progress. In an instance in which I made three 

 incisions into the cartilage of the patella, and two into that of 

 the trochlear surface of the femur, no adhesion had taken place 

 in any of the instances when the parts were examined twenty- 

 nine weeks afterwards, though no inflammation of the joint, 

 dislocation, lameness, or other apparent cause for the want of 

 union had occurred. Yet some of the cut surfaces were in 

 such close contact, before the parts were examined by means 

 of sections, as to lead to the supposition that union had taken 

 place. On the examination of these wounds, no effused matter 

 of any kind appeared on the perfectly smooth cut surfaces; 

 but as the cells near to them in the substance of the cartilage 

 were obviously enlarged and rounded, having in their interior 

 three or four corpuscles into which their nucleus appeared to 

 have divided, or a number of bright granules, there appears 

 reason to believe that union might still have occurred had more 

 time been allowed. 



" After the foregoing observations, I no longer entertain the 

 slightest doubt that wounds in articular cartilages are capable of 

 perfect union by the formation of fibrous tissue out of the texture 

 of the cut surfaces. The essential parts of the process afjpear to 

 be the softening of the intercellular substance of the cartilage, 

 the release of the nuclei of its cells, the formation of white 

 fibrous tissue from the softened intercellular substance, and of 

 nuclear fibres, by the elongation of the free nuclei. It does not 

 appear necessary that the ceUs should become much enlarged 

 or crowded with corpuscles, for the union may take place with- 

 out any enlargement of the cells, or increase in the number of 

 their corpuscular contents ; these changes, therefore, though they 

 contribute materially in some cases to the rapidity of completion 

 of the process under consideration, are clearly not essential in 

 any of its stages." 



When the destructive process has removed the whole depth of 

 the cartilage to the bone, and when the laminal layer has been 

 removed, the breach is repaired by an exudation from the 

 vessels of the bone, which, becoming converted into bony 

 matter, occupies the affected part. 



