CARTILAGE. 163 



cartilages of the trachea and bronchial tubes, the cartilages of the ribs, 

 and the ensiform cartilage of the sternum. When partial ossific depo- 

 sits take place, it is usually in the substance of cellular, rather than in 

 that of fibrous cartilage. 



269. When the intercellular substance, instead of being homogeneous, 

 has a fibrous character, the tissue called Fibro- Cartilage is produced ; 

 and this may be either elastic or non-elastic, according as the yellow or 

 the white form of fibrous structure prevails. In some instances, the 

 fibrous structure is so predominant over the cellular, that the tissue 

 has rather the character of a ligament than of a cartilage. The white 

 fibrous structure is seen in all those cartilages, which unite the bones by 

 synchondrosis, and which are destined not merely to sustain pressure, 

 but also to resist tension. This is the case especially in the substances 

 which intervene between the vertebrae, and which connect the bones of 

 the pelvis; these in adult Man are destitute of cartilage-corpuscles, ex- 

 cept in and near their centres ; but in the lower Vertebrata, and in the 

 early condition of the higher, the fibrous structure is confined to the 

 exterior, and the whole interior is occupied by the ordinary cartilage- 

 corpuscles. The yellow-fibrous or reticulated structure is best seen in 

 the epiglottis, and in the concha of the ear ; in the former of these, 

 scarcely any trace of cartilage-corpuscles remains ; and in the latter, 

 the cellular structure is only to be met with towards the tip. 



270. We have seen that the elements of the cellular tissues hitherto 

 described, do not come into direct contact with the blood-vessels. The 

 Epidermic and Epithelial cells are separated from them by the conti- 

 nuous layer of basement-membrarie, which forms the surface of the true 

 skin, of the mucous membranes, of the glandular follicles produced 

 from them, &c. In like manner, the cells of Adipose tissue are formed 

 within membranous bags ; around which the blood-vessels form a 

 minute network. The cells of Cartilage are not nourished in any 

 more direct manner ; and are sometimes at a considerable distance from 



Fig. 40. 



Vessels situated between the attached synovial membrane, and the articular cartilage, at the point 

 where the ligamentum teres is inserted in the head of the os femoris of the human subject, between the 

 third and fourth months of foetal life ; a, the surface of the articular cartilage ; 6, the vessels between 

 the articular cartilage and the synovial membrane ; c, the surface to which the ligamentum teres was 

 attached; d, the vein; e, the artery. 



the nearest vessels. It is certain that the substance of the permanent 

 cellular Cartilages is not permeated, in a state of health, even by the 

 minutest nutrient vessels ; none such being brought into view under the 



