CONNECTIVE-TISSUE CORPUSCLES. 105 



mass, is of a dull yellow color and extremely extensible and 

 elastic; when purest nearly as much so as a piece of india- 

 rubber. Sometimes it appears under the microscope to be 

 made up of delicate membranes, but most often it is in the 

 form of fibres (Fig. 43) which are coarser than those of 

 white fibrous tissue and frequently branch and unite. It 

 is unaffected by acetic acid and does not yield gelatin when 

 boiled. 



Connective-Tissue Corpuscles. The fibres of white fi- 

 brous tissue, wherever it is found, are united into bundles 

 by a structureless ground material known as the cement sub- 

 stance, which also invests each bundle, or skein as we may 

 call it, with a delicate coating. In this ground sub- 

 stance are numerous cavities, branched and flattened in 



FIG. 44. Connective-tissue corpuscles. 



one diameter, and often intercommunicating by their 

 branches. In these cavities lie nucleated masses of proto- 

 plasm (Fig. 44), frequently also branched, known as the 

 connective-tissue corpuscles. These it is which build up 

 the tissue, each cell in the course of development forming 

 around it a quantity of intercellular substance, which sub- 

 sequently becomes fibrillated in great part, the remainder 

 forming the cement. The cells do not quite fill the cavi- 

 ties in which they lie, and these opening into others by 

 their offsets there is formed a set of minute tubes ramify- 

 ing through the connective tissues ; and (since these in 

 turn permeate nearly all the Body) pervading all the organs. 

 In these cell cavities and their branches the lymph flows 

 before it enters definite lymphatic vessels, and they are ac- 



