The finer Anatomy of the Nervous Sj^stem of Myxine glutinosa. 391 



preparations, two cells are found, which send their processes into 

 the dorsal root of the anterior Acustic nerve. 



In a haematoxylin preparation from the rostral part of the spinal 

 cord I have found a similar cell, the process of which enters the 

 sensory spinal nerve. 



There are two Acustic nerves in Myxine, a fact first discovered 

 by G. Retzius (40) and he named these nerves Ramus anterior and 

 Ramus posterior acustici. Each has its own ganglion, that of the 

 Ramus anterior is large and miniscus-sbaped, being situated in close 

 contact with the Medulla oblongata; that of the Ramus posterior 

 has not much greater diameter than the nerve itself but is of good 

 length. 



The central distribution of the Acustic nerves is relatively very 

 complicated, even more so than that of the Trigeminus. From the 

 ganglion of the Ramus anterior spring three different roots, the Radix 

 dorsalis, the Radix lateralis and the Radix posterior rami anterioris 

 acustici. The Radix dorsalis leaves the dorsal edge of the ganglion 

 and enters the sensory region with a strong bundle of fibres (Fig. 12 

 R^VIII^). Some of the fibres of this bundle end in the Ganglion 

 centrale nucleus posterior, some most probably decussate, but the 

 bulk run in a horizontal direction towards the dorsal and medial 

 surface of the Corpus restiforme, being joined on the way by the 

 fibres of the Ramus posterior as well as some sensory fibres of the 

 Trigeminus. On arrival at this point part of the fibres run rostrally 

 and end in the gray matter of the most rostral part of the Corpora 

 restiformia; the rest turn in a caudal direction along the medial 

 surface of the Oblongata (Fig. 18). During their caudal course the 

 fibres turn suddenly sideways in a right angle (Fig. li r.f.T 'III ^) 

 and end in the gray matter on all sides of the tract, but part of 

 the fibres can be followed to the Ganglion centrale superior, where 

 they probably end. 



The Radix lateralis enters the Medulla from the centre of the 

 Miniscus. The fibres do not run quite horizontally but in a slightly 

 dorsal direction and after a little while some of them bifurcate 

 (Figs. 12 and 13). Some turn in a rostral, others in a caudal, direc- 

 tion (Fig. 20). The rostral ones continue far up into the Corpus 

 restiforme and end in a conglomeration of small cells — the Nucleus 

 anterior acustici — situated near the medial surface of the Medulla 

 (Fig. 20 tir.ant. VHP). The caudal ones do not seem to enter any 

 special nucleus but lose themselves amongst the gray matter. 



