544 DAVIDSON BLACK 
With regard to the cause of this rostral displacement, Kappers 
(1. ec.) has noted that in teleosts the occipito-spinal nucleus, like 
that of the abducens nerve, occupies its most rostral position 
among those forms in which the optic reflex systems are most 
highly developed (e.g., Pleuronectidae). It would appear prob- 
able, however, that the rostral migration of the occipito-spinal 
motor complex in teleosts has been determined by influences 
quite independent of those acting similarly upon the abducens 
nucleus. 
In teleosts the general cutaneous components of the trigeminus 
and vagus nerves pass caudad in the radix descendens trigemini 
to their chief nucleus of termination in the immediate vicinity 
of the funicular nuclei (Herrick, 38, 40 and 41). Though in 
Ameiurus some of the trigeminal fibers end in relation to the 
deeper layers of the facial lobe (39), by far the greater number 
end in the terminal nucleus in the funicular region. The rostral 
portion of the funicular region in all bony fishes becomes a center 
of the highest importance for the correlation of the tactile im- 
pressions originating in the head and trunk. The long conduc- 
tion paths of the dorso-lateral fasciculus arise in this center from 
which also emerge numerous ventral arcuate fibers to establish 
immediate reflex connection with the subjacent somatic motor 
nucleus. 
In the discussion of the funicular region in Prionotus (1. ¢.) 
Herrick draws attention to Sherrington’s observation: ‘‘ Broadly 
speaking, the degree of reflex spinal intimacy between afferent 
and efferent spinal root varies directly as their segmental prox- 
imity”’ (89, p. 158). At the rostral end of the cord, however, 
owing to the changes brought about by the phylogenetic re- 
duction of the precervical segments, the dominant reflex influ- 
ence of the first sensory segmental nerves upon the motor column 
has been to a large extent suppressed and in its place is substi- 
tuted that of the funiculo-trigeminal area. Thus it would ap- 
pear that the position of the rostral end of the occipito-spinal 
nucleus is determined primarily by that of the nucleus of the 
descending trigeminal root and the associated funicular nucleus. 
