20 ANATOMY FOR NUKSES. [CHAP. III. 



Elastic or yellow fibro-cartilage is tougher and more flexible 

 than hyaline cartilage; it only occurs in parts of the throat 

 and ear. 



White fibro-cartilage is found wherever great strength com- 

 bined with a certain amount of rigidity is required; thus we 

 find it joining bones together, the most familiar instance being 

 the flat round plates or disks of fibro-cartilage connecting the 

 bones of the spine and the pubic bones. White fibro-cartilage 

 very closely resembles white fibrous tissue. 



Cartilage is not supplied with nerves, and very rarely with 

 blood-vessels. Being so meagrely supplied with blood the vital 

 processes in cartilage are very slow, and when a portion of it is 

 absorbed in disease or removed by the knife, it is regenerated 

 very slowly. A wound in cartilage is usually at first healed by 

 connective tissue proper, which may or may not become grad- 

 ually transformed into cartilage. Nearly all cartilages receive 

 their nourishment from the perichondrium which covers them, 

 and which is a moderately vascular fibrous membrane. 



Bone. Bone is a connective tissue in which the intercellular 

 or ground substance is rendered hard by being impregnated 

 with mineral salts. 



On sawing up a bone it will be seen that it is in some parts 

 dense and close in texture, appearing like ivory, whilst in 

 others it is open and spongy, and we distinguish two forms of 

 bony tissue, the dense or compact, and the spongy or cancel- 

 lated. On closer examination, however, it will be seen that 

 the bony matter is everywhere porous, and that the difference 

 between the two varieties of tissue arises from the fact that the 

 compact tissue has fewer spaces and more solid matter between 

 them, arid that the cancellated has larger cavities and more 

 slender intervening bony partitions. In all bones the compact 

 tissue, being the stronger, lies on the surface of the bone, and 

 forms an outer shell or crust, whilst the lighter spongy tissue 

 is contained within. The shafts of the long bones are almost 

 entirely made up of the compact substance, except that they 

 are hollowed out to form a central canal the medullary canal 

 for the reception of the marrow. Marrow is also found in 

 the spongy portions of the bone in the spaces between the bony 

 partitions. 



The hard substance of all bone is arranged in bundles of 



