1 66 



THE TISSUES. 



Heart muscle and nominated muscle receive their motor nerve- 

 supply from neurones of the sympathetic nervous system. The 

 cell-bodies of these neurones are situated in sympathetic ganglia ; 

 the neuraxes, the majority of which form nonmedullated nerve- 

 fibers, branch repeatedly, forming primary and secondary plexuses 

 which surround the larger or smaller bundles of heart muscle-fibers 

 or involuntary muscle-cells. From these plexuses, naked, vari- 

 cosed axis-cylinders, or small bundles of such, penetrate between 

 the heart muscle-fibers or involuntary muscle-cells, also forming 



Fig. 131. Motor nerve-ending in striated voluntary muscle of a frog ; methylene- 

 blue stain (infra vitam) (Huber, DeWitt) : A, Surface view ; B, cross-section ; s, s, 

 sarcolemma ; /, neurilemma. 



1 s \ J 



\ 



Fig. 132. Motor nerve-ending on 

 heart muscle-cells of cat ; methylene-blue 

 stain (Huber, De Witt). 



Fig. 133. Motor nerve-ending on 

 involuntary nonstriated muscle-cell from 

 intestine of cat ; methylene-blue stain 

 (Huber, De Witt). 



plexuses. The fine fibers of this terminal plexus give off from 

 place to place small, lateral twigs, which end on the muscle-fiber 

 and muscle-cells. In heart muscle these lateral twigs may end in 

 one or two small granules, or in a small cluster of such granules 

 (Fig. 132); in involuntary, nonstriated muscle the ending is very 

 simple, the small lateral twigs terminating in one or two small 

 granules. (Fig. 133.) 



Sensory Nerve-endings. The sensory nerve -endings are, in 

 their essentials, the peripheral telodendria of dendrites of peripheral 



