260 



THE HEART, BY F. SCHWEIGGER-SEIDEL. 



is left but to isolate the nerves by dissolving out the network 

 of muscle cells. 



If specimens be taken from the middle of the ventricular wall 

 of Mammals, we may obtain, in successful cases, numerous 

 nerve fibres, though usually only in fragments, and may see how 

 frequently they divide, and, with great clearness, the mode in 

 which they form networks (fig. 42). The divisions are, in some 



Fig. 42. 



Fig. 42. Isolated nerve fibres from the muscular substance of the 

 wall of the ventricle. From the Dog. Magnified 500 diameters. 



parts, very numerous (a), though the lateral branches are for the 

 most part torn off. We seldom meet with such a case as is repre- 

 sented at b, and when seen, there must always remain a doubt 

 whether a natural termination is under observation, because 

 the fibrils issuing from the second nuclear swelling are so fine 

 that no sure ground is afforded to determine whether or no 

 they are broken off. In the Frog, the arrangement is so far 

 different that no capillaries exist in the muscular mass, and 



