VOL. XLII.] PHILOSOPHICAL TRANSACTIONS. 6Qi 



present age, we shall find, that an ulcerated cartilage is universally allowed to 

 be a very troublesome disease; that it admits of a cure with more difficulty 

 than a carious bone ; and that, when destroyed, it is never recovered. Hil- 

 danus, in considering these diseases, has observed, that when the cartilages of 

 a joint were destroyed, the bones commonly threw out a cementing callus ; and 

 thus a bony anchylosis, or immoveable continuity, was formed where the move- 

 able joint had been. So far as he had opportunities of examining diseased 

 joints, either after death or amputation, he had found, according to the nature 

 and stage of the disease, the cartilages in some parts redish and lax ; or soft and 

 spongy ; or raised up in blisters from the bone ; or quite eroded, and perhaps 

 the extremities of the bones carious ; or, lastly, a bony anchylosis formed. But 

 he could never see, nor indeed hear of, the least appearance of an exfoliation 

 from the surface of the cartilage. Now, if we compare the texture and morbid 

 phenomena of those cartilages together, all the diseased appearances will admit 

 of as rational a solution, as perhaps any other part of the vitiated economy. 



It appears from maceration, that the transverse fibrils are extremely tender 

 and dissoluble ; and that the cohesion of the parts of the straight fibres is 

 stronger than their cohesion with the bone. When a cartilage therefore is in- 

 flamed, and soaked in purulent matter, the transverse or connecting fibres will 

 the soonest give way, and the cartilage becomes more or less red and soft, &c. 

 If the disorder goes on a little longer, the cartilage does not throw off a slough, 

 but separates from the bone, where the force of cohesion is least, and where 

 the disease soon arrives, by reason of the thinness of the cartilage. When the 

 bone is thus exposed, the matter of the ulcer, or motion of the joint, corrodes 

 or abrades the bony fibres. If the constitution is good, these will shoot forth 

 a callus ; which either cements the opposite bones of the articulation, or fills 

 up the cavity of the joint, and for the future prevents motion. But if, unfor- 

 tunately, the patient labours under a bad habit of body, the malignancy, having 

 got root in the bone, will daily gain ground, the caries will spread, and at last 

 the unhappy person must submit to extirpation, a doubtful remedy, or wear 

 out a painful, though probably a short life. 



Explanation of the figure. Fig. 4, pi. 18, represents a view of the patella on 

 the backside, where it is covered with a smooth cartilage. In this we may ob- 

 serve, AAAA, the surface of the cartilage, appearing, when the perichondrium 

 is removed, like velvet. Near the middle, part of the cartilage is taken out, in 

 order to show b, the subjacent surface of the bone ; and c, the thickness of the 

 cartilage, where the perpendicular fibres are seen very distinctly ; d, the 

 scabrous lower point of this bone, into which the ligament is inserted that binds 

 it to the tibia. 



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