The brain of Acipenser. 183 
I believe that this tract has not been recognized. It will be much 
more difficult to recognize because from the Amphibia onward the 
tract must be small and probably scattered among the arcuate fibres 
after decussation, and because the fasciculus communis (fase. soli- 
tarius) is itself imbedded among the nuclei from which those fibres 
originate. I believe, however, that further investigation will bring 
to light a secondary vagus tract in higher Mead: comparable 
to that in fishes. 
b) No final conclusions can at present be reached with regard 
to the second and third questions. In discussing the representative 
of the lobus vagi in the cord in my previous paper (98b, p. 596—597) 
I made the statement that it did not continue into the cord, since 
it was mesial to the dorsal horns and ended in the dorsal raphe 
immediately behind the commissura infima Halleri, and that there 
was no demand for such a center in the cord since it was the center 
for splanchnic nerves and no sensory fibres supplying the viscera 
entered the cord. The former statement seems to require modi- 
fication in accordance with the above description of the cervical 
bundle. At the time of writing the paper referred to, CAJAL’s paper 
(96) was not accessible to me and I had no preparations in which 
these structures attracted my attention. The cervical bundle with 
the cells accompanying it seems to be a direct continuation of this 
system. CaJAL has followed it only to the end of the pyramidal 
decussation, that is to about the level of the first cranial nerve. It 
is very desirable that further attempts be made to trace these tracts 
through the cord. In the statement that there was no need for this 
system in the cord, I was in error owing to too little acquaintance 
with the literature of the sympathetic system. The evidence for the 
existence of sensory fibres in the dorsal roots of the spinal nerves 
distributed to viscera by way of the sympathetic system is reviewed 
by Huser (97). The central course and ending of these fibres is 
unknown. The most natural hypothesis is that they are of the same 
character as the sensory fibres of the VII, IX and X cranial nerves 
distributed to viscera, and that the sympathetic fibres should find in 
the cord a special end-nucleus similar to that of these cranial nerves 
in the medulla. The cells of this nucleus, if it exists, should be 
found continuous with the cervical bundle and its cells, and may be 
situated in the vicinity of the dorsal commissure or of CLARKE’s 
column. 
The third question is the main one raised by the following 
