162 MR. TOYNBEE ON THE ORGANIZATION AND NUTRITION 



The First Class of Non-vascular Animal Tissues. 

 Of Articular Cartilage and Fibro- Cartilage. 



The tissues which I have placed in the first class are articular cartilage, and fibro- 

 cartilage ; but in reference to the latter, the cartilaginous portion only can be consi- 

 dered as non-vascular. These tissues are analogous to each other in their situation, 

 structure, mode of nutrition and functions. Each of them forms a part of joints, and 

 is subject, in the performance of its functions, to concussion and compression, and is 

 composed of corpuscles or cells possessing similar characters. Although they are 

 properly considered as non-vascular tissues, they appear to be pervaded by blood- 

 vessels at an early period of their development, or perhaps it would be more correct 

 to say, that as growth proceeds, the cartilage increases, so as to occupy the space 

 which had previously been permeated by vessels. 



I have been able to demonstrate that vessels are never found within these carti- 

 lages when fully developed, but at that period vessels form convolutions in their 

 immediate vicinity. These vessels are separated from articular cartilage at adult 

 age by a layer of bone, and in fibro-cartilage, at the same period, they uniformly 

 terminate within the boundary of its fibrous tissue. Over a certain portion of the 

 free surface of both of these tissues blood-vessels extend, but they do not penetrate 

 into their substance. 



The investigations which are about to be detailed, lead, I think, to the certain con- 

 clusion, that articular cartilage in the adult state is principally nourished by fluid 

 derived from the vessels of the cancelli of the bone to which it is attached, which 

 exudes through the coats of those vessels, and makes its way into the substance of 

 the cartilage through the intermediate lamella of bone. The cartilage of fibro-carti- 

 lage is nourished in like manner by liquor sanguinis, derived from vessels situated 

 in the contiguous fibrous portion. The vessels ramifying in a certain extent of the 

 free synovial surface of both these species of cartilage contribute doubtless to their 

 nutrition, but not to near the same extent as do the vessels of the opposite side. 

 With respect to the actual process of nutrition in these cartilages, I shall only observe 

 here, that the cells of these structures must be regarded as having the function which 

 has been ascribed to those of all non-vascular tissues, viz. that of promoting the cir- 

 culation of, and modifying, the nutrient liquor. In connection with this process, how- 

 ever, it will be seen, that articular cartilage presents in its adult state very minute 

 canals, which may be regarded as existing for the reception of the nutrient fluid, and 



Owen's Odontography : — " But since every secretive process, and the development of the primordial cells of 

 every tissue are due to changes produced in the liquor sanguinis, transuded from and beyond the sphere of the 

 ultimate capillaries, the absence of these vessels in the dense dental substance is as little conclusive against its 

 vital and organized nature, as it would be to prove the inert condition of the germinal membrane of the ovum 

 before the thirtieth hour of incubation." — p. 13. 



