166 J. B. JOHNSTON, 
The first and second end in the substance of ROLANDO, the third 
continue into the cord and their fate is unknown. These fibres of 
the third set become mingled with the secondary vagus (“vago-tri- 
geminal”) tract, and I have no doubt that they correspond to the 
secondary vagus tract described in the present paper (page 87). If it 
is true that dorsal tract fibres pass forward into the spinal V tract, 
they must find endings in the acusticum. But it may be that the 
fibres of which MAYSER speaks are in reality spinal V fibres which 
pass through the nucleus to end in subsequent segments of the cord. 
This course for a part of the spinal V fibres would be not at all 
surprising and would account for the statement of authors (MAYSER, 
GORONOWITSCH, KINGSBURY) that the dorsal tracts do not wholly 
disappear at the enlarged anterior end of the dorsal horn. MAYSER 
described the spinal V as reciving a bundle of fibres from the X. 
In the partial mingling of the spinal V and secondary vagus 
tracts Acipenser ruthenus agrees with the carp. GORONOWITSCH 
(89) describes the enlarged anterior end of the dorsal horn and the 
medullated fibres surrounding it, as I have described them (page 75). 
The tract of coarse fibres seems to be continuous with the dorsal 
tract of the cord. In the medulla at the level of the IX and X 
roots this bundle of medullated fibres which he designates as the 
bundle y, receives arcuate fibres and gives some fibres to the dorso- 
lateral tract (= tuberculum acusticum). The bundle thus formed 
continues forward to the level of the roots of the trigeminus 
(7. I). GORONOWITSCH seems not to have traced any part of 
this bundle into the roots of the V nerve, but says that it passes 
between the dorsal and ventral roots and continues forward to end in the 
Rindenknoten (secondary vagus nucleus). The presence, in this bundle, 
of fibres which come from the vagus lobe and end in the secondary 
vagus nucleus proves beyond a doubt that it contains fibres cor- 
responding to the secondary vagus tract of Acipenser rubicundus 
(page 87), while the relation of its coarse medullated fibres to the 
nucleus funiculi shows that it contains the spinal V tract which 
GORONOWITSCH has failed to trace into the V root If so, the com- 
plex bundle corresponds to the secondary vago-trigeminal plus the 
spinal V tract of MAYSER. In A. ruthenus the fibres from the two 
sources are somewhat more intimately mingled than in the carp. 
Since writing the above, GORONOWITSCH’s paper on Lota (96) has 
come into. my hands. In this G. recognizes the compound nature 
of his bundle and describes it as I have indicated above. In À. 
