INNERVATION OF THE DIGESTIVE TUBE 177 



ganglion. Within the ganglia the paths of the fibers composing 

 these commissures intersect each other at various angles, while 

 in the commissures the fibers run more or less parallel with 

 each other. In pyridine-silver preparations the slender fibers 

 running in these commissures are stained somewhat more intensely 

 than the surrounding tissue and present a slightly wavy and vari- 

 cose appearance. In those commissures which are composed of 

 a distinct fiber-bundle the fibers are more or less compactly 

 aggregated, while in the more flattened commissures fibers 

 running parallel with each other may often be observed distrib- 

 uted more or less uniformly over areas of considerable width. 

 In transverse or longitudinal sections numerous commissures may 

 be traced between the bundles of circular muscles from the 

 ganglia of the myenteric plexus into the submucous plexus. 



The ganglia of the myenteric plexus vary greatly in size, 

 being composed of relatively few or of relatively many neurones. 

 The neurones are not compactly aggregated. In good pyridine- 

 silver preparations, however, little tissue may be observed in 

 the ganglia except the fibers which pass through them at various 

 angles and the neurones with their processes. Pericellular cap- 

 sules were not observed in these ganglia either in pyridine-silver 

 or in methylene blue preparations. The writer is, therefore, 

 inclined to agree with Miiller ('11) that such capsules do not occur 

 in this plexus. 



The neurones in these ganglia may be studied most satisfactor- 

 ily in sections taken in the plane of the plexus because many of 

 their processes lie approximately in this plane. In good prepara- 

 tions of this kind axones and dendrites may often be traced for 

 a considerable distance from the cell-body. The neurones in these 

 ganglia vary greatly in size as well as in their general character 

 and form. Neurones of distinct types may be observed, but the 

 deviations from such types are so numerous and so varied that 

 one finds little satisfaction in attempting any rigid classification. 

 Perhaps the most significant morphological difference between 

 neurones in these ganglia consists in the length and the distribu- 

 tion of their dendrites. The dendrites of some are long and 

 slender while those of others are too short to be traced out of 



