VOL. XLU.J PHILOSOPHICAL TRANSACTIONS. Qqq 



was necessary, we might instance the flower of any corymbiferous plant, where 

 the floscuh and stamina represent the little bundles of cartilaginous fibres ; and 

 the calyx, on which they are planted, bears analogy to the bone. 



Now these perpendicular fibres make the greatest part of the cartilaginous 

 substance ; but doubtless there are likewise transverse fibrils which connect 

 them, and make the whole a solid body, though these last are not easily seen, 

 because being very tender, they are destroyed in preparing the cartilage. 



We are told by anatomists, that cartilages are covered with a membrane 

 named perichondrium. If they mean the cartilages of the ribs, larynx, ear, 

 &c. there, indeed, such a membrane is very conspicuous ; but the perichon- 

 drium of the smooth articulating cartilages is so fine, and firmly braced on the 

 surface, that there is room to doubt whether it has been often demonstrated, or 

 rightly understood. This membrane, however, Mr. H. had raised in pretty large 

 pieces after macerating ; and found it to be a continuation of that fine, smooth 

 membrane that lines the capsular ligament, folded over the end of the bone from 

 where that ligament is inserted. On the neck of the bone, or between the in- 

 sertion of the ligament, and border of the carwiigp, it is very conspicuous, and 

 may be pulled up with a pair of pincers ; but where it covers the cartilage it 

 coheres to it so closely, that it is not to be traced in the recent subject without 

 great care and delicacy. In this particular it resembles that membrane which is 

 common to the eye-lids and the fore-part of the eye-ball, and which is loosely 

 connected with the albuginea, but strongly attached to the cornea. 



From this description it is plain, that every joint is invested with a membrane, 

 which forms a complete bag, and gives a covering to every thing within the ar- 

 ticulation, in the same manner as the peritonaeum invests not only the parietes, 

 but the contents of the abdomen. 



The blood-vessels are so small, that they do not admit the red globules of the 

 blood ; so that they remained in a great measure unknown, till the art of filling 

 the vascular system with a liquid wax brought them to light. Nor even by this 

 method are we able, in adult subjects, to demonstrate the vessels of the true 

 cartilaginous substance ; the fat, glands, and ligaments, shall be red with in- 

 jected vessels, while not one coloured speck appears on the cartilage itself. In 

 very young subjects, after a subtle injection, they are very obvious ; and Mr. H. 

 found their course to be as follows : all round the neck of the bone there are a 

 great number of arteries and veins, which ramify into smaller branches, and 

 communicate with one another by frequent anastomoses, like those of the me- 

 sentery. This might be called the circulus articuli vasculosus, the vascular 

 border of the joint. The small branches divide into still smaller ones on the 

 adjoining surface, in their progress towards the centre of the cartilage. We are 



VOL. VIII. 4 T 



