94 JoURNAL OF COMPARATIVE NEUROLOGY. 
even into the tertiary branches. They are disposed parallel 
with the course of the dendrites. 
In that side of the cell from which the axone arises, the 
tigroids have a special arrangement. The axone-hillock (Fig. 
47, ax. h.) is an oval mass of finely granular material, and the 
tigroid-bodies are packed rather densely round it. The form 
of tigroid is also less elongated here, merely an irregular lump. 
The axone arises directly from the body of the cell. While 
it is destined to ultimately be a component of either the V, 
VII, IX, or X nerves, it generally takes quite an indirect 
course. The usual way is through the medium of the fasciculus 
longitudinalis dorsalis. An axone passes into this bundle to 
finally emerge at some other level. In Fig. 47, the axone 
passes dorsal to the fasciculus communis. There is a bundle of 
fibres of considerable size lying here, composed chiefly of 
axones which have emerged from the dorsal longitudinal bundle 
to enter the nerve-root. Other axones, but these are few in 
number, may enter the nerve directly. Still others pass into 
a bundle of arcuate fibres and doubtless enter the nerve on the 
opposite side. These several paths to the nerves are shown in 
Big. 2)\v. m. 7. 
The viscero-motor neurones have an internal structure 
which is conspicuously motor in character, the large amount 
of tigroid substance representing much expenditure of energy 
here. The large size of the neurone is evidently the correla- 
tive of the importance which the system assumes in the inner- 
vation of great vital organs. Such innervation requires a nexus 
with viscero-sensory neurones, and the means have already 
been suggested in the preceding subsection, the interlacing of 
the axones from the lobus vagi with the dendrites of the vis- 
cero-motor nucleus. This gives a complete reflex circuit for 
visceral innervation. 
6. General Cutaneous Nucleus and Spinal V Tract. 
The literature of the portion of the oblongata included 
here is in some confusion. The older writers did not have 
methods of investigation which would demonstrate the presence 
