NERVE-TISSUE. 301 



section. Such plexiform terminations are seen in different local- 

 ities beneath the epithelia, in the submucous tissue, and in the 

 connective tissue between the circular and longitudinal muscle- 

 layers of the intestines. (See Fig. 128.) 



The plexus of Meissner is located in the submucous layer of 

 the intestine, and exhibits distinct ganglionic enlargements (see 

 chapter on alimentary canal). 



The plexus of Auerbach is found at the junction of the 

 two muscle-layers of the intestine ; it contains nodular gan- 

 glioiiic bodies with numerous nuclei (see chapter on alimentary 

 canal). 



The axis-cylinders, near their terminations, divide into ex- 

 tremely delicate axis-fibrillm (M. Schultze), which are slender, 

 beaded filaments, representing the bioplasson reticulum in an 

 elongated direction. Their course in the cornea has been accu- 

 rately studied by W. Hassloch (see page 175, Fig. 67). They enter 

 a cornea-corpuscle and inosculate with its bioplasson reticulum, 

 evidently in the same manner in which they originate in the cen- 

 tral ganglionic element. Many fibrillae simply pass through one 

 corpuscle and enter another ; fibrillae have been also traced into 

 the bioplasson reticulum of the basis-substance. Terminations of 

 this kind are found in different connective-tissue formations ; they 

 are not permanent, but may occur from a temporary enlargement 

 and elongation of reticular fibrillae connecting with former nerves. 

 As they are bioplasson formations, they may disappear by falling 

 back into the reticulum. 



The finest plexiform terminations of axis-fibrillae are observed 

 in the walls of capillary blood-vessels, particularly in the cement- 

 substance between the endothelia (W. Tomsa and others). Such 

 plexus formations were found in the epithelia by Pfliiger, Langer- 

 haus, and others, and it is still an unsettled question whether the 

 nerves terminate in the cement-substance between the epithelia, 

 or penetrate the epithelial bodies themselves. 



Peculiar epithelial formations are the gustatory buds 

 (Schwalbe) and the olfactory cells (M. Schultze), the connection 

 of which with nerve-fibers, however, is still a disputed point. 

 Very complicated formations are those of Corti's organ and of 

 the retina. The plates, the " hair-cells," the rods and cones are 

 well known, but how the nerves connect with these is unsettled. 

 In the light of the bioplasson theory we may, at a time not far 

 distant, hope for new discoveries and new views. 



