The brain of Acipenser. 171 
homologized with HERRICK’s spinal VIII. Descending root fibres 
similarly placed in Acipenser end in the acusticum, while se- 
condary arcuate fibres from the acusticum which are of much 
finer calibre than the VIII and lateral line root fibres run in a 
superficial position and cross the middle line in the extreme ventral 
part of the raphe, as do the fibres described by HERRICK (p. 205; 
cf. page 80 of this paper). 
I have shown that the V also ends in large part in the acu- 
sticum. The fibres of what I have called the deep descending tract 
of the V are at least in part indistinguishably mingled with the VIII 
and lateral line fibres, and undoubtedly find their endings in the 
same intimate relations. HERRICK’s description of the deep tract 
of the V is scarcely satisfactory. He says (p. 201): “A large bundle 
accompanies the motor root nearly to the middle line and constitutes 
the ‘deep portion of the descending V’ of JOHNSTON (98). Most of 
these fibres, both sensory and motor, pass at once to the opposite 
side through the commissura accessoria, but some of the motor fibres 
terminate in, or more strictly, arise from, the motor V nucleus and 
the fasciculus longitudinalis dorsalis of the same side. The sensory 
fibres of this bundle probably also, in part, cross to the opposite 
side, though they could not be separately followed. Some of them 
appear to end in a compact nucleus of very small cells lying very 
near to the motor V nucleus and a little farther caudad. This I 
take to be the chief sensory nucleus of the trigeminus. It should 
be stated, however that my knowledge of this nucleus and its con- 
nections is not as precise as that of the other roots described. No 
considerable number of trigeminal fibres turn cephalad from the 
nerve. The nucleus lying under the cerebellum to which JOHNSTON 
traced sensory trigeminal fibres in Acipenser was found, but no fibres 
were traced to it, nor were the descending fibres described by him 
and by GoRONOWITSCH discovered. No GOLGI preparations were 
made, and I can not deny the presence of such fibres in relatively 
small numbers, as this region has not been exhaustively studied.” 
Without GoLGr preparations I regard the description of root fibres 
passing to the other side as lacking sufficient foundation. HALLER 
(98) also describes such fibres, but the great number of other 
statements in his paper which require confirmation make one hesitate 
to accept his testimony on this point. I do not know any cells in 
Acipenser corresponding to HERRICK’S chief sensory nucleus of the 
trigeminus, and can not agree with HERRICK that the deep de- 
