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 otoHths 

 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." 1 



It goes against the grain to differ with such a charmful 

 and theme-ful author as Sir Herbert Maxwell. But his 

 conclusion 2 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 ehminate any vibration set up by its 



' British Fish : Salmonidcs (London, 1887), p. 19. 



'■^ Memories of the Months, Fourth Series (London, 1914). PP- 232-3. 



