CARTILAGE. 



319 



tilage, and they usually do not anastomose with each other. Similar 

 canals are also seen in the temporary cartilages near the points 

 where the process of ossification is going on. 



The changes undergone by the cartilaginous skeleton, will be spe- 

 cified under the head of the development of bone. 



Pathological States, and New Formations of Cartilage. 



1. As cartilage normally contains no vessels, nor passages for the 

 circulation of plasma (like bone and the cornea), it can hardly be 

 regarded as capable of being attacked by inflammation. It is, how- 

 ever, susceptible of ulceration, or a gradual removal of its substance, 

 and in this condition appears to become vascular on the eroded sur- 

 face. The vessels are, however, not in the substance of the carti- 

 lage, but in a membranous expansion which is formed de novo on 

 its rough surface. 



2. The loose cartilages, so called, which are often found in joints 

 (especially the knee-joint), are not actual cartilages, but merely the 

 non-vascular processes of the synovial membrane, which increase 

 in size and solidity and then become detached from the vascular 

 folds. Sometimes, however, they are mere fibrinous exudations, or 

 solidified deposits from the synovia, as Yirchow has shown. 



3. A new formation of cartilage constitutes enchondroma. It 

 occurs in bone more frequently than in any another normal tissue. 

 The bones of the fingers and toes are most liable to it, though the 

 ribs, sternum, and vertebrae are not exempt; and the cranium, the 

 ilium, and the long bones have been attacked by it. 



Enchondroma may originate on the surface of bone, or in the 



Fig. 207. 



Fig. 209. 



Fig. 207. Thin section of the circumference of an enchondroma from the pelvis. 



Fig. 208. Cells from the softened part of the same tumor. 



Fig. 209. The same, after the addition of acetic acid. (Bennett.) 



cancellated tissue. It usually grows slowly and seldom exceeds an 

 orange in size. . It is not attended by pain or disorganization of the 



