158 



H. E. JORDAN AND K. B. STEELE 



8 



Fig. 7 Longitudinal section of cardiac muscle of bat, showing a granular 

 intercalated 'disc' running across eight fibers. 



Fig. 8 Heart muscle of bat showing two long step-like discs winding super- 

 ficially around their fibers. The 'risers' probably represent anisotropic granules 

 aligned longitudinally, or perhaps a distorted membrane of Heidenhain. 



