548 



MOVEMENTS. 



farther illustrated by the remarkable experiments of M. Oilier, upon transplantation of 

 this membrane in the different tissues of living animals. 



Physiological Anatomy of Cartilage.-lu this connection, the structure of the articu- 

 lar cartilages presents the chief physiological interest. The articular surfaces of all the 

 bones are encrusted with a layer of cartilage, varying in thickness from -^ to ^ of an 

 inch. The cartilaginous substance is white, opaline, and semitransparent when examined 

 in thin sections. It is not covered with a membrane, but in the non-articular carti- 

 lages it has an investment analogous to the periosteum. 



Examined in thin sections, cartilage is found to consist of a homogeneous fundamental 

 substance, marked with numerous excavations, called cartilage-cavities, or chondroplasts. 

 The intervening substance has a peculiar 

 organic base, called cartilagine. By pro- 

 longed boiling this is changed into a new 

 substance, called chondrine. The organic 

 matter is united with a certain proportion 

 of inorganic salts. This fundamental sub- 

 stance is elastic and resisting. The car- 

 tilages are closely united to the subjacent 

 bony tissue. The free articular surface 

 has already been described in connection 

 with the synovial membranes. 



Cartilage- Cavities. These cavities are 



FIG. 167. Section of cartilage from the rib of the ox, 

 shmcing the homogeneous fundamental substance, 

 cartilage-cavities, and cartilage-cells; magnified 

 370 diameters. (From a photograph taken at the 

 United States Army Medical Museum.) 



FIG. 168. Perpendicular section of a diarthrodial 

 cartilage. (Sappey.) 



1,1, osseous tissue; 2,2, superficial layer of osseous 

 tissue treated with hydrochloric acid ; 3, 3, cavities 

 and cells of the deep layer of cartilage ; 4, 4, cavities 

 and cells of the middle layer; 5, 5, cavities and ceils 

 of the superficial layer. 



rounded or ovoid, measuring from y^y to ^ f an mcn i Q diameter. They are gener- 

 ally smaller in the articular cartilages than in other situations, as in the costal cartilages. 

 They are simple excavations in the .fundamental substance, have no lining membrane, 

 and contain a small quantity of a viscid liquid, with one or more cells. They are entirely 

 analogous to the lacuna of the bones. 



Cartilage- Cells. Near the surface of the articular cartilages, the cavities contain each 

 a single cell ; but in the deeper portions the cavities are long and contain from two to 

 twenty cells arranged longitudinally. The cells are of about the size of the smallest 

 cavities. They are ovoid, with a large, granular nucleus. They often contain a few 

 small globules of oil. In the costal cartilages the cavities are not numerous but are 



