Low to obtain it. 271 
ringing of a bell, we have heard of fish being summoned to a meal 
by the performance, and I have often heard this story brought up 
as a direct proof of fish being able to hear. I once had a visitor 
who was so sure that the fish, when trained to do so, would obey 
the summons, that I at length told him that I had some ponds 
full of fish that would do the same, but when I explained that it 
made not the slightest difference to them whether the tongue of 
the bell happened to be in or out, even he began to be less 
credulous. Having procured a bell, and removed the tongue, I 
went out for his satisfaction and pretended to ring it, when the 
fish came at once. 
Although no notice is taken of sounds made in the air, yet 
we find that trout are keenly sensible to vibrations of the water, 
which are probably transmitted to the body of the fish, and there 
is little doubt that noises made in the water are heard by the trout 
in this way. Dr. Francis Day, in his British and Irish 
Salmonide” (p. 19), says :—“ Hearing is developed in fishes, and 
it is very remarkable how any diversity of opinion can exist as to: 
their possessing this sense.” A little further on he says :—“ But 
the chief mode in which hearing is carried on must be due to the 
surface of the fish being affected by vibrations of the water, and 
the sounds are transmitted directly to the internal ear, or else by 
means of the air bladder acting as a sounding board.” Here we 
must leave this interesting question. Its bearing on the cultivation 
of trout is rather an important one, as cases may often arise in 
which the fish might.be so disturbed by noises as to be injuriously 
affected thereby. But it is not so, for as regards noises made in 
the air the fish are neither alarmed when feeding, nor yet driven 
off their spawning beds, provided always that they see nothing. 
Some scientists have supposed the lateral line to have some 
connection with the hearing powers of fish, hence it has been 
called “the lateral sensory apparatus.” It consists of a series 
of punctures forming tubes from which nerves run, and com- 
municate with the head and possibly with the organs of hearing. 
These tubes also discharge a mucous secretion. 
Do fishes sleep? is a question I am sometimes asked. That 
some fishes do there can be little doubt, but whether sleep is to 
them what it is to the mammalia is another thing. Trout cannot. 
