80 [May I, 



unlikely that a part of the numerous nuclei in the neighbourhood 

 belong to the nerve-fibres. 



Simultaneously with the increase of its terminal fibres the dark- 

 bordered parent fibre doubtless augments in thickness, which explains 

 the fact, otherwise difficult to understand, that it is invariably of 

 much larger size than the nerve-fibres proceeding to the other 

 muscular fibres. 



From what has been stated it will thus be seen that the relation of 

 the nerve to the peculiar structures described does not support the 

 views of Kuhne. 



On the Termination of the Nerves in the Involuntary Muscles, and 

 on the disposition of the Nerves in the Heart of the Frog. 



Having, to the best of my power, investigated the ending of the 

 nerves in voluntary muscles, I thought it right to extend my re- 

 searches to those of the involuntary muscular organs, respecting the 

 ultimate terminations of which very few, if any, satisfactory observa- 

 tions have been heretofore made known. 



The muscles I selected for examination were those of the heart and 

 pharynx of the frog, and the methods of preparing them were the 

 same as for the voluntary muscles. 



The nerves of the frog's heart are the two nervi vagi or pneumogas- 

 trics, which, having reached the heart at the place where the venous 

 sinus joins with the right auricle, enter the septum between the two 

 auricles, and proceed therein to the ventricle. During this part of their 

 course the two trunks of the vagi, which join together at their entrance 

 into the heart, are almost everywhere beset with numerous ganglionic 

 cells. These cells in some parts form larger masses, well described 

 by Bidder several years ago*. One or two of these masses lie in the 

 upper part of the septum, and may be called the " superior auri- 

 cular ganglions " ; another is situated in the lower part of the septum, 

 near the ventricle, the "inferior auricular ganglion"; and a very re- 

 markable and constant ganglion is seated in each of the two larger 

 valves placed between the ventricle and the auricles, these are the 

 " ventricular ganglia " of Bidder. 



Apart from these larger ganglionic masses on the trunks of the 

 vagi, there are found, although without regular arrangement, gangli- 

 * Muller's Archiv, 1852. 



