CONNECTIVE TISSUES 13 



phoid elements. It forms the connecting layer beneath the 

 skin, the submucous and subserous tissues, and the layer be- 

 tween the muscles. It receives its name on account of the 

 areolse or spaces within its substance, which permit the adja- 

 cent 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. o. Bundles of the white fibers of 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 mem- 

 branes 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 transparent and finally invisible. 



