THE SILENCE OF THE SEA 73 



waters of Cuba, comninnioates Avith its companions in the same way. 

 Doras and several other South American cat-fishes have a special 

 adaptation for the production of sound, Jcnown as the elastic spring 

 meclianism by which the wall of the swim-bladder is made to vibrate. 



JMuscles pass from the skull to the springs which are attached to 

 the bladder and the contraction of these muscles causes the springs 

 and the \\alls of the bladder to vibrate and to produce sound. There 

 are other sounds of a very different nature produced by certain 

 fresh- water fishes. These are the breathing sounds or " bruits de 

 souffle." as described by Dufosse, and are said to occur in the eels, 

 the carj), several species of loach, and the European cat-fish Silurus 

 glanis. 



According to Dufosse, quoted in the Cambridge Natural History, 

 '* these sounds originate in some cases from the expulsion of gas 

 from the air-bladder through the pneumatic duct and mouth, and 

 in others as in the loach Misgurnus fossilis, they are produced by 

 the rapid expulsion tlu'ough the anus of bubbles of air previously 

 taken in at the mouth. 



In conclusion, we must add that it is believed that both the cod 

 and the haddock produce sounds through the medium of the swim- 

 bladder. This is certainly true of the rock-haddock as we shall see 

 later. The above examples of noises made by fishes clearly prove 

 that the silence of the sea is not complete, and also give good grounds 

 for attributing a sense of hearing to many fish hitherto considered 

 to be deaf. But there is other evidence pointing to the suscepti- 

 bility of fishes to noises, but the conditions in this case are artificial. 

 We allude to certain methods adopted by fishermen designed to drive 

 the fish into their nets ; the first example to be given is a method, 

 not well laiown, of catching herring. It has been described to the 

 writer by one of the most experienced and observant of the skippers 

 of steam-drifters fishing out of Lowestoft. 



Observations on the reaction of the herring to loud noises prove 

 that the immediate response is to dive. The Whitby and Scar- 

 borough fishermen employ a purely local method of fishing called 

 " beating for herrings." In August the fish are found some ten 

 miles from the shore in thirteen fathoms of water ; late in the even- 

 ing the fishermen put out to sea and, keeping a close watch, they 

 wait till they see the surface of the water alter in colour and character 

 as the mass of herring gradually " swim " or rise to the surface. 

 They at once steam or row into the midst of this area, and shoot 

 their nets ; as they so do every bucket, tin can, or shovel available, 

 is used to make a din by beating against the sides of the vessel, 

 accompanied by shouts and yells. 



