6 H. BERKELBACH VAN DER SPRENKEL 
in the arrangement of the motor nuclei.. The results justify 
this expectation, as appears from the topographic diagrams 
appended to this paper (fig. 21). 
The arrangement is characteristic of a ‘taste fish,’ and shows 
this character in a very pronounced way. I have thought it 
necessary to give also a description of the sensory roots and their 
connections, first because such a description, though given in 
Herrick’s paper for the North American forms, has not yet been 
given for the European representative of the siluroids, and 
second, because a knowledge of the sensory roots, centers and 
secondary paths is absolutely necessary for the understanding 
of the topography of the motor nuclei. Herrick’s excellent 
description of Ameiurus has been a valuable guide to me, the 
more so since I had a complete series of Ameiurus nebulosus at 
my disposal. 
After ‘having finished my work on Silurus, it seemed interest- 
ing to me to examine another fish, whose physiological char- 
acteristics were very different from those of Silurus. I chose 
Mormyrus caschive, whose motor nuclei have not yet been de- 
scribed and which is, moreover, an interesting object on account 
of the enormous development of the lateralis nerves and valvula 
cerebelli. The study of the latter has also enabled me to correct 
some statements occurring in the literature concerning this 
peculiar brain. 
The Central Institute for Brain Research in Amsterdam has 
put at my disposal series of sections through the brains of Silurus 
glanis and Mormyrus caschive. The objects, embedded in cel- 
loidin, were cut into sections of 25 micra and alternately stained 
after van Gieson and Weigert-Pal. The Weigert-Pal series was 
counterstained with paracarmine. 
My projections have been made after the van Gieson series. 
In order to get the most exact reconstruction of the topographic 
positions of the motor nuclei and roots, I projected them on the 
sagittal plane lying medially in the raphé in the following way. 
In each section the distance from the ventral border of the bulb 
to the floor of the fourth ventricle was measured with an ocular 
