44 
The Lateral Line of Fishes. 
[January, 
occurrence even among the latter, we may rest confident 
that the chance of our destruction from this cause alone is 
very small ; so small, in faCt, that we shall be quite safe in 
concluding that our planet will have a very long lease of 
existence indeed. 
VI. THE LATERAL LINE OF FISHES. 
By M. G. de Sede. 
ff? . 
S||T is familiarly known that the name of “ lateral line ” 
has been given by ichthyologists to an organ which 
runs along each side of almost all fishes, extending 
from the head to the tail. It has been successively studied 
by Steno, Lorenzini, Petit, Redi, Leydig, and Schulze, the 
latter of whom have indicated the true path to be followed 
for the discovery of -the functions of this line, whilst they 
have almost completed the investigation of its anatomy. 
M. de Sede, in a thesis recently maintained before the 
Faculty of Sciences at Paris, and reproduced in “ Cosmos 
les Mondes,” gave an account of certain interesting experi- 
ments made for the purpose of elucidating the physiological 
function of this curious organ. 
The fishes selected for the experiment were first submitted 
to the aCtion of an anaesthetic, and then underwent the 
operation of re-seCtion of the lateral nerve, which excited 
no reflex aCtion due to pain. When resuscitated the sub- 
jects were left at rest in a large bowl, and some days after- 
wards they were placed in a vast aquarium where everything 
is so arranged that a fish desirous of circulating freely must 
make use of all its tactile resources and means of guidance. 
Under these conditions it was observed that the fishes which 
had been operated upon moved only with great caution, and 
were almost always the last to arrive at the distribution of 
food. Thus it appears that a fish able to make use of its 
eyes, but deprived of its lateral line, experiences a certain 
difficulty in finding its way. 
M. G. de Sede next sought to ascertain how a fish would 
aCt if it retained the use of its lateral line, but was deprived 
of sight. 
