38 



THE ESSENTIALS OF HISTOLOGY. 



The connective tissues include areohir tissue, adipose tissue, elastic 

 tissue, fibrous tissue, retiform and lymplwid tissue, cartilage and lone. 

 All these tissues agree in certain microscopical and chemical characters. 

 They, for the most part, have a large amount of intercellular substance 

 in which fibres are developed, and these fibres are of two kinds : white 

 and yellow or elastic. Moreover, there are many points of similarity 

 between the cells which occur in these several tissues ; they are all 

 developed from the same embryonic formation, and they tend to pass 

 imperceptibly the one into the other. Besides this, their use is every- 

 where similar; they serve to connect and support the other tissues^ 

 performing thus a passive mechanical function. They may therefore be 

 grouped together, although differing considerably in external characters. 

 Of these connective tissues, however, there are three which are so 

 intimately allied as to be naturally considered together, being composed 

 of exactly the same elements, although differing in the relative develop- 

 ment of those elements ; these are the areolar, elastic, and fibrous 

 tissues. Adipose tissue and retiform tissue may both be looked upon 

 as special modifications of areolar tissue. Areolar tissue being the 

 commonest and, in a sense, the most typical, its structure may be 

 considered first. 



FIG. 39. GROUND SUBSTANCE OF 



FIG. 38. BUNDLES OF THE WHITE FIBRES OF AREO- CONNECTIVE TISSUE STAINED 

 LAR TISSUE PARTLY UNRAVELLED. (Sharpey.) BY SILVER. (The cell-spaces 



are left white. ) 



Areolar tissue. The areolar tissue presents to the naked eye an 

 appearance of fine transparent threads and laminae which intercross in 

 every direction with one another, leaving intercommunicating meshes, 

 or areolae, between them. When examined with the microscope, these 



