102 



THE TISSUES. 



minute spaces between the fibrils in these bundles, are occupied by 

 a semifluid, homogeneous substance known as the ground-substance, 

 or matrix. The fibrous elements of areolar connective tissue are, 



Reticulum. 



Fig. 64. Reticular connective tissue from lymph-gland of man ; X 



preparation. 



Brush 



therefore, imbedded in this ground-substance. In dense are- 

 olar connective tissue the fibrous elements appear to have 

 nearly displaced the ground-substance. In the ground-substance 

 are found irregular, branched spaces, cell-spaces, in which 

 lie the cellular elements of this connective tissue. These spaces 

 anastomose by means of their branches, thus forming part of a 



system of spaces and small chan- 

 nels, known as the lymph canal- 

 icular system. These spaces and 

 channels permeate the ground- 

 substance in all directions, and 

 serve to convey lymph to the 

 tissue elements. The cell-spaces 

 and their anastomosing branches 

 can be demonstrated by immers- 

 ing areolar connective tissue 

 (preferably from a young animal), 



Fig. 65. Areolar connective tissue 

 from the subcutaneous tissue of a rat. 

 Elastic fibers not shown. 



spread out in a thin layer, in a 

 solution of silver nitrate (i^) 

 until the tissue becomes opaque. 

 If then the tissue is exposed to 



sunlight, the silver is reduced in the ground-substance, giving it a 

 brown color, while the cell-spaces remain unstained. The ground- 

 substance of areolar connective tissue contains mucin. 



