581 



1) The base of the medulla. The impregnation of neurites here 

 is less perfect than in any other part of the brain. The ventro- 

 lateral tracts seem to be made up of the neurites of commissural and 

 tract cells as described for the spinal cord of Selachians and Teleosts 

 by V, Lenhossek, Martin, Aichel, Van Gebuchten, and Retzius. 

 In the posterior part of the medulla at least, these cells are directly 

 comparable with the same cells in the cord. In the anterior part of 

 the medulla some of the commissural cells seem to come into the 

 service of the sensory nerves and of other tracts so as to form special 

 nuclei. 



About the issuing roots of the hypoglossal nerve a number of 

 cells are grouped into a nucleus identified by Goronowitsch ('88) 

 with the lower olive of human anatomy. In relation with these cells 

 end fine fibres from among the fibres of the spinal Vth. bundle. The 

 neurites of the olive cells cross to the opposite side to end among 

 the tract cells of the lateral columns. 



The fasciculus longitudinalis posterior is shown in outline in 

 Figs. 1 — 7. It is made up of coarse medullated fibres, the smaller 

 number of which come from the central difi"use nucleus of the thalamus, 

 and the greater number of which come from the motor cells of the 

 ventral horn along the course of the fasciculus in the medulla. It 

 gives immediate origin to the Vlth., to the larger part of the ventral 

 root of the Vllth., to the whole of the ventral roots of the IXth. 

 and Xth., and to the Xllth. nerve, as shown in Figs. 3, 4, and 7. 

 The mode of origin of the Vlth. is like that of the Xllth. A part 

 of the ventral root of the Vllth., all of the ventral Vth., as well as 

 the IVth. and lllrd., arise from cells lying in the latero-dorsal portion 



Fig. 1. 



Fig. 2. 



Lobus vagi 



Nuc. acust. spinal. 



Nuc. funic. 



et trig, spinal. 



Com. inf. Halleri 



Lobus vagi 



Nuc. acust. spinal. 



Nuc. funic. 



et trig, spinal. 



Sec. Vagus bundle 



Maüthner's fibers Mauthner's fibers 



~ Ventral horn 



"Fasc. long. post. Fasc. long. post. 



