72 CONNECTIVE TISSUE CARTILAGE BONE 



syncytial network with a mucin-like substance in its vacuoles ; and finally 

 it becomes cellular and closely resembles cartilage/*' 



The Perichondrium. The perichondrium is a dense fibrous mem- 

 brane which surrounds each individual plate of cartilage. It is continuous 

 with the surrounding connective tissue, and is well supplied with blood- 

 vessels and lymphatics ; it may also contain terminal nerve fibrils. 



The cartilage itself is an absolutely bloodless and nerveless tissue. 

 Neither are lymphatic channels demonstrable within the cartilage matrix. 



FIG. 85. NOTOCHORDAL TISSUE. 



A, from pig embryo of 150 mm.; ther syncy tium contains many mucin-filled spaces. 

 X 800. B, from nucleus pulposus of an adult pig; the three cells shown are greatly 

 vacuolated. X 452. (After L. W. Williams, Amer. Jour. Anat., 8, 3, 1908.) 



After long maceration or artificial digestion the matrix assumes a granu- 

 lar or fibrous appearance, and small channels have been demonstrated 

 within it, which have been said to connect the various lacunas; but it is 

 evident that these appearances were possibly the result of artificial de- 

 structive processes and could not therefore be considered as evidences of 

 the presence of such structure in living cartilage. 



BONE 



General. Bone is a firm calcareous tissue which is found only in 

 the skeletal system. In the flat bones it forms a double layer of dense 

 osseous tissue between which is a narrow space, bridged across at fre- 

 quent intervals and thus subdivided into a number of compartments, the 



