xxii JouRNAL OF ComPaARATIVE NEUROLOGY. 
by a slight mass movement of the water against them. They are not 
stimulated by sound waves such as stimulate the ears. ‘ 
g. Individuals in which the nerves to the lateral-line organs have 
been cut swim downward and thus escape from regions of surface wave 
action. ‘They also orient perfectly in swimming against a current. 
Since surface waves and current action stimulate fishes in which the 
nerves to the lateral-line organs and to the ears have been cut, these 
motions must stimulate the general cutaneous nerves (touch). 
10. The vibrations from a bass-viol string when transmitted to 
water stimulate the ears and the lateral-line organs of Fundulus. They 
also stimulate mackerel and menhaden, but not the smooth dog-fish, 
which responds only when in contact with solid portions of an aquarium 
subjected to vibrations. 
We have another interesting set of observations in Professor 
TULLBERG’S paper on the Functions of the Labyrinth in Fishes.’ 
The author operated on various teleosts by cutting the semi-circu- 
lar canals, removing the large otolith and in various other ways and 
concludes that the labyrinth is not an organ of equilibrium, or of the 
static sense or for the maintenance of muscular tone or of the 
spacial sense in the sense of v. Cyon. It is probably to some degree 
an auditory organ (though he gives no satisfactory proof of this). 
‘Originally and primitively, however, the labyrinth of fishes is a sense 
organ for the perception of movements of the surrounding water, since 
currents are apparently perceived by the cristae acusticae of the am- 
pullae, but wave movements probably by the maculae acusticae of the 
utriculus, the sacculus and the lagena. The central organ for this 
sense organ is apparently the cerebellum.” 
That the labyrinth is primarily an organ for the perception of cur- 
rents or streaming movements of the surrounding medium seems on 
a priort grounds highly improbable, since the stimulus is one which 
may easily act upon the skin, lateral-line organs or other superficial 
sense organs, but only with difficulty on the deep-seated labyrinth. 
Moreover the experiments cited seem inconclusive. In the first 
place, the canals were merely cut and the nerve endings were not de- 
stroyed. The same applies to the removal of the otolith. In several 
of these experiments there were forced movements and disturbances of 
equilibrium which the author has to explain away. In general too the 
lesions were symmetrical. More radical operations would seem to be 
? TycHo TULLBERG. Das Labyrinth der Fische, Ein Organ zur Empfindung 
der Wasserbewegungen. SBithang till K. Svenska Vet.-Akad. Handlingar, Stock- 
holm, Bd. 28, Afd. IV, No. 15, 1903. 
