OF NON-VASCULAR ANIMAL TISSUES. 167 



The articular cartilage, above described, is gradually being converted into bone 

 during the whole of life ; thus it is thicker in young than in adult subjects, and, as Sir 

 Benjamin Brodie informs me, it is much thinner in old age than in the adult : in fact, 

 it is not very rare to find tliat the articular cartilage of the head of the os femoris in 

 very old persons has completely disappeared ; a change which is probably to be attri- 

 buted to its entire ossification*. 



Of the Nutrient f^essels of Articular Cartilage during its development, which are 

 situated betwixt it and its Synovial Membrane. — Previous to giving a description of 

 the vessels which are present on the articular cartilage, and which are between it 

 and the synovial membrane investing it, I must here state that I believe that the 

 synovial membrane is extended over the surface of th^ articular cartilage. The valu- 

 able pathological researches of Sir B. Brodie have induced me to adopt this opinion ; 

 in addition to which, in favour of this view, the following accounts of dissections made 

 by Henle and myself may be cited. 



Henle says, "The epithelium is continued in a thinner layer on the articular sur- 

 faces of the cartilage, on which it is separated from the cartilage-corpuscles by a thin 

 layer of cellular tissue-}-." 



In a foetal Calf, towards the latter part of uterine existence, I have removed the 

 synovial membrane from nearly the entire surface of the articular cartilage of the 

 condyle of the femur, to which it was attached by a considerable layer of cellular 

 tissue, in which the blood-vessels that are about to be described were seen to 

 ramify. 



These vessels have been alluded to by Dr. W. Hunter under the name of " circulus 

 articuli vasculosus" in the following words J: — "All around 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 mesentery. 



"This might be called the circulus articuli vasculosus, the vascular border of the 

 joint. The small branches divided into still smaller ones upon the adjoining surface, 

 in their progress towards the centre of the cartilage. We are seldom able to trace 

 them into its substance ; because they terminate abruptly at the edge of the cartilage, 

 like the vessels of the albuginea oculi when they come to the cornea." 



The following is an account by Cruveilhier of the injection of these vessels § : — 

 "Nous avons fait, MM. Breschet, Bogros et moi, des injections partielles et g^n^- 

 rales chez de tr^s jeunes sujets ; et chez des adultes, des injections partielles avec 

 une solution d'ichthyocolle color^e avec I'indigo. Les synoviales ont ^t6 parfaite- 

 ment inject^s ; tout autour du cartilage articulaire existe un cercle art^riel duquel 

 partent de tr^s petites ramifications qui s'avancent sur ce cartilage dans I'espace d'une 



* This appears to be another of the many instances of the disappearance of the animal, and the increased de- 

 posit of the earthy constituents of the body in old age. 



t MiJLLER's Archives, 1838, p. 116. t Philosophical Transactions, 1743. 



§ Observations sur les cartilages diarthrodiaux, Archives G^n^rales de Medecine, vol. iv. p. 162, 1824. 



