190 Journal of Comparative Neurology. 



Arnstein, who first stained the cardiac muscle in methylene 

 blue, describes their ending on the heart muscle cells without 

 an end-bulb. " Dann sieht man den varicosen Faden sich an 

 die Muskelzelle ansetzenohne eine Endausschwellung zu bilden," 

 are his words on this point. Jacques, who has quite recently 

 reported on the heart muscle nerves as seen when stained with 

 methylene blue, makes the following general statement concern- 

 ing their ending : "From the intra-muscular fibers, terminal 

 fibers arise, which penetrate between the cells of the muscle 

 bundles and enter into communication with them by means of 

 terminal and lateral branches of varied form and size, compar- 

 able for the most part to the terminations described in striped 

 muscle of invertebrates." The endings sketched by him in 

 Fig's. 10, 15 and 16 (young rat) and Fig. 14 (cat) of Plate 

 XVIII, while resembling somewhat those given by us, are all 

 somewhat coarser, showing larger end-bulbs — mushroom-like 

 endings as stated by him-^— when compared with ours. 



The simple ending shown in Fig. 1 5 resembles very close- 

 ly the endings shown in Fig's. 6 and 7, Plate XV, of Retzius' 

 article, showing the nerve ending in the cardiac muscle of the 

 mouse when stained with the Golgi method. The more com- 

 plex endings mentioned are not discussed nor diagramed by 

 him. 



Further contributions on the cardiac nerves stained with 

 the Golgi method have been made by Ramon y Cajal and Azou- 

 lay ; their results are however known to us only through re- 

 views. Ramon y Cajal, who has stained the cardiac nerves of 

 reptilia, batrachians and mammals, recognized a pericellular 

 plexus, comparable to that found in smooth muscle. He states 

 that the fibrils are devoid of myelin and beset with varicosities 

 and attach themselves to the striated substance and end on its 

 surface in small enlargements. Azoulay has studied the cardiac 

 nerves in the human embryo ; but reached no definite conclu- 

 sion as to their ultimate ending. 



Motor endings in involuntary muscle tissue. The endings of 

 nerve fibers in involuntary muscle tissue have been the subject 



