CHAPTER VIII. 



CAKTILAGE AND CONNECTIVE TISSUE. 



Temporary and Permanent Cartilages. In early life a 

 great many parts of the supporting framework of the Body, 

 which afterwards become bone, consist of cartilage. Such for 

 example is the case with all the vertebrae, and with the bones 

 of the limbs. In these cartilages subsequently the process 

 known as ossification takes place, by which a great portion of 

 the original cartilaginous model is removed and replaced by 

 true osseous tissue. Often, however, some of the primitive 

 cartilage is left throughout the whole of life at the ends of 

 the bones in joints where it forms the articular cartilages; 

 and in various other places still larger masses remain, such as 

 the costal cartilages, those in the external ears forming their 

 framework, others finishing the skeleton of the nose which is 

 only incompletely bony, and many in internal parts of the 

 Body, as the cartilage of " Adam's apple/ 7 which can be felt 

 in the front of the neck, and a number of rings around the 

 windpipe serving to keep it open. These persistent masses 

 are known as the permanent, the others as the temporary 

 cartilages. In old age many so-called permanent cartilages 

 become calcified that is, hardened and made unyielding by 

 deposits of lime-salts in them without assuming the histo- 

 logical character of bone, and this calcification of the perma- 

 nent cartilages is one chief cause of the want of pliability and 

 suppleness of the frame in advanced life. 



Hyaline Cartilage. In its purest form cartilage is flexi- 

 ble and elastic, of a pale bluish-white color when alive and 

 seen in large masses, and cuts readily with a knife. In thin 

 pieces it is quite transparent. Everywhere except in the 

 joints it is invested by a tough adherent membrane, the peri- 

 chondrium, which resembles in structure and function the 

 periosteum of the bones. When boiled for a long time in 

 water, such cartilages yield a solution of chondrin, which 

 differs from gelatin in minor points, but agrees with it in the 

 fact that its solution in hot water " sets " or gelatinizes on cool- 



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