166 MR. TOYNBEE ON THE ORGANIZATION AND NUTRITION 



be described, towards the articular cartilage, Plate XIII. figs. 1 and 2*. Some of 

 these canals are of a large size, and are frequently considerably dilated at their blind 

 extremities. They do not penetrate into the substance of the articular cartilage. 

 These canals are for the reception of branches of sanguiferous vessels. When the 

 epiphysis is minutely injected, the depressions upon its surface will be found to con- 

 tain congeries of convoluted blood-vessels, which are more drawn out the deeper the 

 depression, until at length, in the interior of the canals and their divisions, single, 

 \ and nearly straight vessels are found. These epiphysal vessels has^e a very peculiar 

 / disposition. They consist of an artery having a course more or less straight, which 

 ' terminates in a dilatation, or in convoluted branches, from which the vein arises, 

 Plate XIII. figs. 3 and 4. From the fact of the presence of these vessels, which 

 • converge towards and form convolutions internal to the articular cartilage, it may 

 be inferred that they supply the cells of the latter with a nutrient fluid. As the arti- 

 cular cartilage increases in thickness, and the ossific nucleus which is developed in 

 the epiphysal cartilage becomes larger, these vessels gradually recede from between 

 them, and they leave a considerable mass of non-vascular cartilage between the osse- 

 ous nucleus and the synovial membrane ; all of this appears to be articular cartilage, 

 which is now nourished by the vessels in the interior of the nucleus. See Plate XIII. 

 figs. G, 7, 8, 9 and 10. The supply of blood-vessels in thecancelli of the osseous nucleus, 

 is remarkably abundant ; they are large and are separated from the surrounding car- 

 tilage by an extremely delicate lamina of bone, which is principally made up of osseous 

 cells. I am induced to believe that at this stage of development, as in adult age, the 

 fluid passes from the bone into the cartilage and nourishes it. From the difficulty of 

 obtaining a series of specimens, I am unable to state the exact period at which this 

 change in the position of one set of vessels, and the additional function in the other, 

 takes place ; but it most probably occurs at diffiirent periods in the various articula- 

 tions, and it is effected in all by the time that they are called upon to encounter con- 

 cussion, compression, &c. to any extent. 



It may be here observed, that the articular cartilage at this early period of life is 

 thicker than in the adult state. Although devoid of canals for the reception of blood- 

 . vessels, it presents numerous minute canals, which pervade that portion of it con- 

 \ tiguous to the osseous nucleus, and they course from the latter towards the synovial 

 membrane, which however they do not reach. The true nature of these canals could 

 only be examined by powers magnifying between one and two hundred diameters. 

 They are minute and extremely numerous; they divide, subdivide, and communicate 

 with each other and form dilatations. The parietes of these canals present distinct 

 rounded cells, which in some places are arranged in rows and groups. The substance 

 between these tubes is transparent, and contains no corpuscles. 



< 



* To obtain a distinct view of these canals, the epijjhysis should be macerated in water for a short time, so as 

 to remove the perichondrium which invests it ; this was done to the specimen from which the drawing was 

 taken. 



