460 "Journal of Comparative Neurology and Psychology. 



nerve enters at the upper and posterior segment lying between the 

 cutis and membrana propria and accompanying the artery. It 

 divides into two branches, one of which goes to the anterior seg- 

 ment, the other to the posterior and inferior segment. In addition, 

 numerous small branches enter with blood vessels at different 

 points of the periphery. The larger ramifications of these nerves, 

 which lie between the cutis and the membrana propria, he calls the 

 ground plexus. (2) From the ground plexus nonmedullated nerves 

 pass to form a plexus along the blood vessels. These may end 

 in the vessel wall or pass to help form the subepithelial plexus. 

 In addition, from the ground plexus large fibers pass off in whose 

 course he notes ganglion cells from which fibers pass both to the 

 blood vessels and to the subepithelial plexus. From the subepi- 

 thelial plexus fibers may be seen to pass between the epithelial 

 cells; how they end w^as not known. (3) The mucous membrane 

 lining of the membrana is w^ell supplied with nerves; its subepi- 

 thelial plexus receives its nerve supply both from the ground plexus 

 and from the tympanic plexus. 



Jacques ('00), using intravitam methylene blue, agrees in the 

 main with Kessel, but states that, (i) The submucous plexus 

 appears less developed than the cutaneous. (2) The plexus is 

 most dense in the posterior superior quadrant. (3) The fibers 

 of the plexus are nonmyelinated like those of the cornea. (4) 

 Ganglion cells do not exist. The terminations he finds are com- 

 plicated arborizations of the general type of peripheral sensory 

 endings; certain libers probably penetrate into the epidermis. 

 He states that his researches must be regarded as incomplete, 

 inasmuch as he has not been able to fix the exact position of the 

 impregnated tissue. 



IF. Calamida ('01 ) used the rapid Golgi, the chloride of gold 

 and the methylene blue (intravitam) methods. He agrees with 

 Jacques and distinguishes, (i) A subcutaneous plexus, lying 

 between the cutis and the membrana propria, derived from the 

 n. auriculo-temporalis and from the n. vagus, which consists of 

 two parts: {a) a vascular plexus; [h) a subepithelial plexus. (2) 

 A submucous plexus, lying between the mucous membrane and 

 the membrana propria, supplied from the tympanic plexus as 

 well as from the n. auriculo-temporalis and the n. vagus. It also 

 consists of two parts: [a] a lymphatic plexus; [b] a subepithelial 

 plexus. These two plexuses are connected both by the vascular 



