804 Baron Cuvier on the Physiological: Labours 
attention of naturalists, to determine the true nature of the 
different tubercles which compose the brain of fishes. a 
We have given an account more than once, and especially 
in 1820, of the doubts which exist with respect to those two 
tubercles which are interior to the cerebellum, and are generally 
hollow, containing in the interior one or two pair of smaller 
tubercles. ‘These have long been considered to be the true 
brain, the tubercles which they cover, to be the tubercula 
quadrigemina, and those placed anterior to them the olfactory 
tubercles, analogous to those which we find in front of the 
cerebrum in the rat, mole, and other mammalia. 
For some years M. Arasky, and subsequently M. Serres, 
have come to the conclusion, but from anatomical comparison 
only, that the anterior tubercles constitute the cerebrum, and 
that the large hollow pair correspond to the tubercula quadri- 
gemina. It follows from the experiments of M. Flourens made 
on carps, that irritation of the anterior tubercles, or of the su- 
perior part of the hollow tubercles, produces no convulsions, 
but if the base of the last be pricked, violent spasms are in- 
duced ; which would also lead us to consider the lesser internal 
tubercles to be tubercula quadrigemina, as well as the hollow 
tubercle which incloses them. ‘Lhe removal of the anterior 
tubercles does not at first perceptibly change the animal’s con- 
dition or manner; but it appears to move less frequently. and 
not voluntarily; it even appeared to the author, as well as he 
could judge from the state of restraint in which he was obliged 
to keep the fish thus mutilated, that it could neither hear nor 
see. ‘The removal of the hollow tubercles produces a much 
more decisive effect on the ceconomy of the animal; it moves 
no longer, respires with difficulty, and lies on its back or side. 
M. Flourens does not hesitate to conclude that it is to the tu- 
bercula quadrigemina that these hollow tubercles correspond, 
and considers that the great influence which they exert on the 
system of fishes arises from their extraordinary state of deve- 
lopment in this class of animals. With respect to the single 
tubercle which has universally been regarded as cerebellum, it 
exhibits phenomena similar to those of the cerebellum of qua- 
drupeds and birds. Injury of it does not excite convulsions ; 
when removed the fish can scarcely remain on its belly; it 
swims in an extraordinary way; and it turns on its centre as 
birds do who have lost the cerebellum. The protuberances 
which are placed behind the cerebellum in fishes, from which 
their 8th pair of nerves appears to originate, remain to be ex- 
amined; those which in the superior. classes afford only doubt- 
ful or imperceptible analogies. Irritation of all. their parts 
produces. violent convulsions, particularly in the opercula of 
. the 
