VOLUNTARY MUSCLE. 



57 



are called muscle-columns, sarcostyles, OY fibrils. When stained with 

 chlorid of gold transverse lines are also seen uniting the granules, 

 the whole arrangement of lines presenting a reticular appearance, 



FIG. 4S. Striated muscle-fiber of frog, showiug sarcoleinma (Huber). 



which, however, Schafer regards as in reality not a network, but 

 only the optical expression of the interstitial substance between 

 the muscle-columns, and which is called sarcoplasm. 



If a muscle-fiber is examined in cross-section, it is found to be 

 divided into angular areas, Cohnheim's areas (Fig. 51). These are 



FIG. 49. Voluntary muscle (Leroy). A, Three voluntary fibers in long sections: 

 a, three voluntary muscle-fibers; b, nuclei of same; c, fibrous tissue between the 

 fibers (endomysium) ; d, fibers separated into sarcostyles. B, Fiber (diagrammatic): 

 a, dark band ; b, light band ; c, median line of Hensen ; d, membrane of Krause ; 

 e, sarcolemma; /, nucleus. C: a, Light band; 6, dark band; c, contracting ele- 

 ments ; d, row of dots composing the membrane of Krause ; e, slight narrowing of 

 contracting element aiding in production of median line of Hensen. 



the cross-sections of the muscle-columns or sarcostyles, between 

 which is the sarcoplasm. 



Hensen's line is a line crossing a muscle-fiber in the middle of 



