168 MR. TOYNBEE ON THE ORGANIZATION AND NUTRITION 



demi ligne a une ligne, mais qui s'arretent toujours dans le point precis, ou la syno- 

 viale cesse elle meme d'etre indistincte." 



The arteries passing between the synovial membrane and the articular cartilage 

 may be considered as the terminal branches of the articular vessels. 



Before they reach the articular cartilage they are but laxly covered by the synovial 

 membrane, but at the border of the cartilage they are firmly bound down to it by the 

 very small quantity of dense cellular tissue existing between them. It is difficult to 

 state generally at what period of foetal existence the vessels, which have been spoken 

 of in the first stage as forming convolutions around the joints, are prolonged upon its 

 surface, and I can only here give the result of my investigations upon the subjects 

 which I have been able to inject and examine. 



I have studied with care the stages by which these vessels are prolonged upon the 

 head of the os femoris at the point where the ligamentum teres is attached. 



At between the third and fourth months of foetal life, these vessels are simply a mass 

 of delicate convolutions situated beneath the synovial membrane ; at ihejifth month 

 these convolutions are somewhat unravelled, so as to extend over the surface of the 

 cartilage to the distance of about half a line (Plate XIIL fig. 11.) ; and at between the 

 seventh and eighth months they are drawn out and prolonged to the distance of a 

 line and a half, Plate XIV. fig. 1 . At this stage, these vessels consist of arteries of 

 considerable size, which radiate in a straight course from the attachment of the 

 ligamentum teres. They give off but few branches, and, previous to terminating, 

 they divide and subdivide, but do not diminish much in size. They terminate by 

 turning and forming loops with the small veins. Subsequent to the eighth month, 

 these vessels begin to recede in their course ; and at birth, and the periods sub- 

 sequent to it, they are again found to be gathered immediately around the point of 

 attachment of the ligamentum teres. After these vessels have receded, the posi- 

 tion they occupied at the more early periods may be for some time detected by the 

 white aspect of the cellular tissue between the cartilage and the synovial membrane. 

 In the knee-joint of the human foetus of five months, these vessels extend to a con- 

 siderable distance over the surface of the articular cartilage, and in the foetus at 

 birth, although they have receded considerably, they still occupy the inferior surface 

 of the articular cartilage (Plate XIV. fig. 2.) ; in adult age they have entirely receded 

 from it. 



These vessels in the knee-joint have a different mode of distribution from those 

 above-mentioned in the hip. The arteries take a straight direction towards the 

 centre of the articulation, and in their course they give off small branches, which, in 

 the space between them, form a delicate network, and communicate with small veins. 

 These arteries terminate either by turning in their course and forming broad loops 

 with the venous radicles, or they empty themselves into a single vessel from which 

 the veins arise, Plate XIV. fig. 2. 



