

CONNECTIVE TISSUE. 159 



instead of being fibrous, is composed of ribbon-like formations, 

 as in the periosteum; and in others it is disposed of in flat 

 layers, as in the cornea. In many instances we meet with an 

 extremely dense basis-substance, termed the elastic substance, 

 which either occurs in the shape of fibers at the boundary of 

 territories, or almost entirely replaces the glue-yielding basis- 

 substance. This formation appears in the shape of either a dense 

 reticulum or a uniform flat layer. Examples of fibrous elastic 

 basis-substance are found in the connective tissue of the derma 

 of the skin, in the periosteum, etc. ; examples of an elastic retic- 

 ulum are furnished by the Lig. nuchae, the adventitial coat of 

 arteries, etc. ; examples of flat elastic layers are found in all the 

 so-called u hyaline or structureless membranes," beneath epithe- 

 lial and endothelial formations, in the sarcolemma, etc. 



The different varieties of fibrous connective tissue may be 

 classified according to the following characteristics : 



Delicate bundles of fibrous tissue, running mainly in one 

 direction, and being separated by a basis-substance of slight 

 density, form the so-called loose connective tissue f. L, in the 

 omentum and the arachnoid; 



Bundles of fibrous connective tissue, interlacing in all direc- 

 tions, produce a felt- work structure f. i., in the derma, the 

 interarticular ligaments, the sclerotic ; 



Coarse bundles arranged in only a longitudinal direction are 

 found in the tendons and in the articular ligaments j 



Flat bundles transformed into ribbons, freely interlacing, 

 appear in the periosteum, the dura mater, the pericardium, and 

 the aponeuroses ; 



A coalesced layer of elastic basis-substance produces a flat, 

 sheet-like formation f. i., in the hyaline or basement layers, and 

 in sarcolemma ; 



Lamellated layers of considerable breadth, freely interlacing, 

 build up the cornea. 



(a) Delicate Connective Tissue Composed of Fibrillce, or of 

 Comparatively Thin Bundles of Fibrittoe. This variety, usually 

 termed " loose connective tissue," is arranged in bundles, in which 

 the fibers are connected by a small amount of a cement-sub- 

 stance, soluble in lime and baryta water. Between the bundles 

 are spaces which contain either a semi-fluid, viscid, myxomatous 

 basis-substance or a lymph-like liquid. These spaces may become 

 expanded by accumulation of a serous liquid, as in oedema, or of 

 air or liquids introduced from without. 



