Herrick, Zevminal Buds of Fishes. » 123 
ment of the water to organs of equilibration and hearing. We 
therefore have structural and physiological evidence that the 
sense organs of the acustico-lateralis system have been derived 
from tactile organs. 
(b) Now turning to the central connections of the acustico- 
lateralis nerves within the brain, we have a quite independent 
line of evidence. It has long been known that these nerves all 
end in the tuberculum acusticum and associated centers, and it 
has recently been shown, particularly by JOHNSTON in an im- 
portant series of papers, that these centers are all derivatives of 
the general cutaneous or tactile centers of the brain. While 
my own studies on the teleosts have shown that in these higher 
fishes the specialization of the acustico-lateralis centers has 
progressed so far as to obscure the primary relations, JoHN- 
STON’s observations on the lower fishes leave no room for doubt 
that the history is as stated above. 
From the concurrent history of both central and peripheral 
relations we are therefore justified in assuming that the neuro- 
masts and their associated nervous apparatus have been de- 
rived from the general cutaneous or tactile system of nerves. 
(3) The terminal buds (end-buds, beaker organs, etc.) are 
by no means on 30 secure a morphological foundation. It is, 
however, now definitely known that they resemble in every es- 
sential respect the taste buds within the mouth cavity. The 
specific sensory cells are not hair cells, but, like the indifferent 
supporting cells, they run through the entire thickness of the 
sensory epithelium from external to internal limiting membrane. 
They may terminate distally in a short stiff bristle, but never in 
the tuft of long hairs characteristic of hair cells. The organs 
usually rest on a raised papilla of dermis, and finally in every 
case where the innervation is accurately known they are sup- 
plied by communis nerves, which have nothing in common 
either centrally or peripherally with the general cutaneous or 
acustico-lateralis systems of nerves. On the other hand, these 
nerves always terminate within the brain in a single center 
(bilobed in some fishes), the vagal lobe (plus facial lobe in silur- 
