DO FISH HEAR ?—EXPERIMENTS T13 
.whether the undoubted effect of their being disturbed by certain 
noises is attained by hearing proper, or by vibration acting 
on the surface part of the fish and communicating instantly 
with the internal ear. 
Day’s summary of the question, still regarded after thirty 
years as fair and conclusive, even if attaching undue importance 
to the fontanelles, is as follows. “‘ Hearing is developed in 
fish, and it is very remarkable how any diversity of opinion 
can exist as to their possessing this sense. The internal 
auditory apparatus is placed within the cranial cavity: its 
chief constituent parts are the labyrinth, which is composed 
of three semi-circular canals, and a vestibule, which latter 
expands into one or more sacs, where the ear bones or otoliths 
are lodged. A tympanum and tympanic cavity are absent. 
They possess fontanelles between the bones, forming the roof 
of the skull, which being closed by very thin bones or skin 
permit sounds from the surrounding water to be readily trans- 
mitted to the contiguous internal ears. But the chief mode in 
which hearing is carried on must be due to the surface of the 
fish being affected by vibration 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 drum.” ! 
It goes against the grain to differ with such a charmful 
and theme-ful author as Sir Herbert Maxwell. But his 
conclusion ? that fish in Loch Ken were disturbed every time 
a shooting party half to three-quarters of a mile away dis- 
charged their guns cannot be reconciled with the experiments 
made by me in July 1918 to test the behaviour of trout, 
when guns were fired, not half a mile away, but quite close 
to them. 
Three of us, all accustomed to watching fish, selected a 
narrow shallow burn in which the trout ran from fingerlings 
up to fish three or four years old. Each in turn fired the gun 
(an ordinary 12 bore C.F.), with the usual shooting charge of 
powder and No. 5 shot. At the first two trials only was the 
shot extracted, so as to eliminate any vibration set up by its 
} British Fish: Salmonide (London, 1887), p. 19. 
* Memories of the Months, Fourth Series (London, 1914), pp. 232~3- 
