INTRODUCTION 



II 



The Master Tissues. The muscular tissue consists 

 chiefly of rows of cells placed end to end (Fig. 10). These 

 cells have the remarkable property of becoming broader 

 and shorter when stimulated by impulses from nerve cells 



The nerve tissue consists 

 of cells with long, spiderlike 

 branches (Fig. n). Some 

 nerve cells have branches 

 several feet long, so long that 

 they go from the backbone 

 to the foot. The branches 

 are called nerve fibers (Fig. 

 142). Nerve fibers which 

 carry impulses to the nerve 

 cells are called sensory fibers. 

 The nerve fibers which carry 

 impulses from the nerve cells 

 are called motor fibers. The 

 organs are set to work by 

 impulses through the motor 

 fibers. Besides these two 

 master tissues there are five 

 supporting tissues. 



Connective tissue, like all 

 other tissues, contains cells 

 (see Fig. 12), but it consists 



FIG. 12. CONNECTIVE TISSUE CELLS, 

 removed from among the fibers of 



fig- 13- 



- 

 n, c, nucleus; /, branches. 



FIG. 13. 



-CONNECTIVE TISSUE 

 FIBERS. 



a, b, bundles of white fibers; c, a yellow 

 fiber. 



chiefly of fine fibers. These 

 fibers are of two kinds, 

 'very fine white fibers which 

 are inelastic, and larger yellow fibers whicJt are very elastic 

 (see Fig. 13). Connective tissue is found in every organ, 

 binding together the other tissues and cells. It is inter- 

 woven among the muscle cells, and the tendons at the 



