[24 



THE BIOLOGY OF THE FROG 



CHAP. 



into gelatin. Scattered among the white fibers there are 

 generally a few yellow elastic fibers ; these are straight and 

 not wavy ; they are not affected by acetic acid and do not 



yield gelatin when 

 boiled ; they fre- 

 quently branch, and 

 when cut across, the 

 ends do not curl like 

 those of the white 

 fibers. Imbedded 

 in spaces of the ma- 

 trix here and there 

 are the connective 

 tissue corpuscles or 

 cells. These cells 

 vary considerably in 

 their form and in 

 the appearance of 

 their cytoplasm ; 



FIG. 32. — Fibrous connective tissue from the US uallv thev are 

 frog, c, connective tissue corpuscles; e, elas- 

 tic fibers; w, white fibers. (After Parker and branched, and the 



Parker.) branches of neigh- 



boring cells often unite or anastomose, forming an irregu- 

 lar network, the meshes of which are filled with the inter- 

 cellular substance. These processes of the cells run in 

 canals which allow a circulation of the fluid among the spaces 

 or lacunae in which the cells lie. White fibrous tissue varies 

 greatly in consistency and texture in different parts. The 

 loose tissue binding the muscles together is called areolar 

 tissue, and is composed of sheets and strands intersecting 

 each other in all planes. It forms a coating or fascia for 

 each muscle, and toward the ends of the muscles it is 

 frequently -modified into tendon which is very dense and 



