HuBER, Sympathetic Nervous System. gj 



(44) we learn that Cajal succeeded in staining the heart nerves 

 in reptilia, batrachians and mammalia, with the rapid Golgi 

 method (personal letter to Retzius), The nerves are described 

 as non-medullated, forming plexuses around the heart muscle 

 fibers, and ending in varicose fibers which terminate on the heart 

 muscle cells in small end bulbs. Retzius' (44) description cor- 

 responds very closely to that given by Cajal and need therefore 

 receive no further mention. Hey mans (49), who cut the frog's 

 heart stained after the Golgi method, into serial sections, 

 reaches the conclusion, based on the richness of the nerve sup- 

 ply, that each heart muscle cell is directly innervated. 



Berkley (46) has studied the ending of heart nerves in the 

 white rat, the frog, sparrow and the dog, using a modified Gol- 

 gi method (tissues were prefixed in picric acid). Berkley 

 describes two kinds of fibers in the inter-muscular plexus — var- 

 icose fibers, of a brownish black color, and fibers rarely show- 

 ing any knotty thickenings and giving off few branches and 

 often showing a rounded or elongated bulb near their termina- 

 tion. Two kinds of endings are described : 



{a) " The end-apparatus of the varicose network is usually 

 very simple, being represented almost without exception by a 

 minute ball-like enlargement at the terminal point of the end- 

 branches." 



(d) The second type of fiber presents an end-apparatus 

 more complex ; "an end-termination of considerable size, lying 

 upon the sarcous substance of a single muscular fiber may be 

 seen." The end-apparatus of the second type is found on the 

 fibers presenting the nodular enlargements above referred to, 

 and Berkley looks upon these nodular enlargements as bipolar 

 cells, situated in the path of the fiber, and suggests as a hypoth- 

 esis that we may here have sensory fibers, either of the sympa- 

 thetic or cerebro-spinal system. 



Jacques (47) has made observations on the intrinsic heart 

 nerves in the frog and mammals, both with the Golgi and me- 

 thylen-blue method. As regards the ultimate ending of the 

 motor nerves he has this to say in his summary : 



' ' The nerve trunks anastomose with each other after their 



