CONNECTIVE TISSUES 13 



elements. It forms the connecting layer beneath the skin, the 

 submucous and subserous tissues, and the layer between the 

 muscles. It receives its name on account of the areolae or 

 spaces within its substance, which admit the adjacent parts to 

 move easily upon one another. It consists of white and yellow 

 fibers in about an equal proportion. 



(3) Fibrous Tissue. This variety includes all the more 

 usual forms of connective tissue found in the various parts of 

 the body. It may be further subdivided into: (a) White fibrous 

 tissue, (b) yellow elastic and (3) loose fibrous or areolar tissue. 



FIG. 9. Bundles of the white fibers or areolar tissue partly unravelled. 

 (Kirkes after Sharpey.} 



(a) White fibrous tissue is composed of groups or bundles of 

 fibers which have a wavy longitudinal striation. It is tough 

 and inelastic and forms ligaments, tendons and membranes in 

 various parts of the body. Chemically this tissue is composed 

 of a complex albuminoid substance, collagen. Upon being 

 treated with acetic acid the fibers become swollen and trans- 

 parent and finally invisible. 



