The brain of Acipenser. 89 
Along the course of the secondary vagus tract, especially near 
its cephalic end it is pierced by the dendrites of numerous tract 
and commissural cells which may receive impulses from those fibres. 
In one series these cells are arranged in three somewhat definite 
groups, which may perhaps be regarded as supplementary nuclei. 
These would correspond to the cells of the lateral columns which 
serve as diffuse end-nuclei for those secondary vagus fibres which 
run caudally. 
The cells in the cephalic part of the lobus vagi, among the in- 
coming VII fibres, require a separate description. They are large 
irregular cells crowded among the bundles of the VII root, their 
dendrites twisting about in zig-zag manner. The cells and their 
large dendrites are surrounded by a network of extremely fine fibres 
whose origin and character are somewhat uncertain. They have the 
form of fine end-branches of nerve fibres and resemble the extremely 
fine end-branchings of the fibres of the bundles of MEYNERT which 
I have determined with certainty. I therefore believe these to arise 
from collaterals of the VII fibres. The neurites of the cells arise 
from the cell bodies or from some of the dendrites and pass back- 
ward along with the VII root fibres. Their destination I have not 
determined. I suppose them to be short neurites which break up 
in the vagus lobe in relation with the cells of the I. type. 
b) Cerebellum. (Phots. 3, 4, 6, 7, 13—16.) 
At the cephalic end of the medulla the acusticum with the 
nucleus of the ascending V bundle forms the entire thickness of 
the dorso-lateral wall. The acusticum is not, however, the most 
dorsal structure, since it is covered by the cerebellar crest and this 
again has above it a thin band of tissue which connects the lobus 
lineae lateralis with the granular layer of the cerebellum, as de- 
scribed above (page 82). Following these structures forward, the 
cerebellar crest makes a sweeping curve upward and forward and 
then inward, becoming continuous with the molecular layer of the 
lateral lobe of the cerebellum. The ridge of granule cells on the 
dorso-lateral surface of the cerebellar crest grows larger and spreads 
out on the cephalo-lateral surface of the lateral lobes of the cere- 
bellum. Here the granular substance is superficial and this part of the 
cerebellum is without any molecular layer. Within the concavity of the 
curve formed by the cerebellar crest, the acusticum continues for- 
ward, upward and inward to become continuous with the granular 
