Huber-DeWitt, Nerve-Endings in Muscles. 191 



of numerous contributions. Since their first description in 1 862 

 by Kolliker, they have been repeatedly investigated by all the 

 current methods. It is thought best to dispense with a review 

 of the now somewhat voluminous literature treating of this sub- 

 ject, since a number of the recent writers, among whom may be 

 mentioned Lustig, Erik Miiller, Retzius, Brenheim and Schultz, 

 have covered the ground very completely. It is now very gen- 

 erally believed that the nerve fibers ending in the involuntary 

 smooth muscle tissue are the neuraxes of sympathetic neurons, 

 situated in, or at some more remote point from, the smooth 

 muscle in which such endings are found. Indeed quite recently, 

 Arnstein was able to sketch an entire sympathetic neuron, the 

 neuraxis of which terminated in the muscle tissue found in the 

 wall of the trachea ; and one of us, as stated in another place, 

 was able to see this now and then, in the sympathetic cells 

 found in Auerbach's plexus in some fishes and reptilia exam- 

 ined by him. This is, however, usually not possible, as the neur- 

 axes and, to some extent, the dendrites also of the sympathetic 

 neurons found in involuntary muscle tissue, are interwoven into 

 such intricate plexuses, that the tracing of a single neuraxis 

 through its terminal branchings becomes impossible. Many 

 writers, following Arnold, have described three plexuses thus 

 formed in involuntary muscle tissue, — a ^r(?z^«^ plexus, an inter- 

 mediary plexus, surrounding the fasciculi or bands of smooth 

 muscle; and an inter-muscular plexus found between the spindle 

 shaped cells. These plexuses are said to anastomose with each 

 other. There is, however, probably no actual anastomosis of 

 the nerve fibers constituting these several plexuses, but rather 

 an interlacement of such fibers. It is, however, not our purpose 

 to dwell on these facts, as they may be quite readily ascertained 

 in gold chloride, chrome silver or methylene blue preparations ; 

 but rather to discuss briefly the more disputed question of the 

 ultimate ending of these nerves in the involuntary muscle tis- 

 sue. Concerning this point, two very contradictory views have 

 been expressed : on the one hand it is asserted more or less posi- 

 tively by Kolliker, Lowit and Gescheiden and in more recent 

 years by Arnstein, Retzius, Erik Mialler, Dogiel and Schultz, that 



