No. I.] THE CRANIAL NERVES OF AMPHIBIA. 167 



from the other fibres of the dorso-lateral tract, to the cere- 

 bellum. A small contingent is derived from the same group 

 of cells that supply a portion of the Acusticus. The exit of 

 this root is somewhat anterior and dorsal to the Facialis and, 

 it may be added from a study of his figures, dorsal also to the 

 Acusticus. 



Besides the ventral root of Trigeminus II he describes its 

 dorsal root which has its source in the lobus trigemini. This 

 latter structure reaches distally as far as the exit of the N. 

 lineae lateralis and is separated from the dorso-lateral by the 

 cerebellar ''ridge." It consists of a central ganglionic mass 

 which furnishes the principal contingent of fibres to the outer 

 layer consisting of fibres. Relations of fibres to other cell 

 groups which are described need not be dwelt upon here. 



Still further cephalad are given off, according to Gorono- 

 witsch, the two roots of ''Trigeminus I." The dorsal fine-fibred 

 root derived from an ascending system, which he has not traced, 

 and a descending system partly to the lateral portion of the 

 cerebellum and partly to the mid-brain. It is to be observed 

 from the figures given that the immediate source of its fibres 

 is ventral to the dorso-lateral tract. It is this root which 

 we have already identified as the homologue mainly of the 

 Trigeminus major of higher forms. Its ventral coarse-fibred 

 root is derived chiefly from the posterior longitudinal fascicu- 

 lus, partly also from some cells lying near the curve made 

 by this bundle as it emerges ("Zwischenzellen "). It will be 

 spoken of later. 



Goronowitsch, in order to overthrow Balfour's hypothesis as 

 to primitive nerves of a mixed type and to show that Bell's law 

 obtains also for the head, points out that the six roots of the 

 facio-trigeminal complex may be arranged in three pairs, each 

 having a fine-fibred dorsal and a coarse-fibred ventral root, 

 namely : — 



Facialis dorsal root from lobus vagi. 



ventral root from posterior longitudinal fasciculus. 

 Trigeminus II dorsal root from lobus trigemini. 



ventral root from dorso-lateral tract. 

 Trigeminus I dorsal root from ascending and descending systems. 



ventral root from posterior longitudinal fasciculus. 



