250 Journal of Comparative Neurology. 



the caudal motor root of the vagus from the ventral horn, 

 as well as from the nucleus ambiguus. Haller ('96) 

 describes and figures from Golgi preparation similar fibres 

 from ventral horn cells (his ventral nucleus of the vagus) 

 in Salmo. I have not found such fibres in Menidia, but 

 no Golgi preparations were made and I cannot deny the 

 possibility of their presence in small numbers. Compare, 

 further, the last paragraph of the discussion of the m. 

 pharyngo-clavicularis externus later in this section. 



iii. — The Motor Glossopharyngeiis. — From the nucleus 

 ambiguus arise also, as in the mammals, the motor fibres 

 of the IX nerve. These fibres arise from the most cephalic 

 part of the nucleus and pass directly cephalad in the same 

 position as that of their cells of origin, i. e. , along the lat- 

 eral surface of the fasciculus longitudinalis dorsalis. 

 This course they maintain for a considerable distance 

 (625-600). Although closely appressed to the fasciculus 

 longitudinalis dorsalis, these fibres can always be distin- 

 guished from it by their smaller size. There is, more- 

 over, always a connective tissue septum between them. 

 In this position the tract from the nucleus ambiguus 

 divides (Fig. 18) into two distinct round bundles of which 

 the dorsal {IX f. I. d.) is the larger. The ventral one 

 alone is the motor IX root {jnot. IX). At 600 this bundle 

 separates to enter its nerve, but the dorsal one continues 

 cephalad in the original position. Here the latter is 

 joined (595) by the motor root of the VII nerve, as 

 described below, and a little farther forward it indistin- 

 guishably fuses with that root and with the fasciculus. 

 The motor IX root after leaving the fasciculus turns 

 sharply caudad and laterad toward its exit, crossing the 

 spinal V tract on the ventral side of the latter. It is 

 joined just after its exit from the oblongata (620) by the 



