160 ANNALS NEW YORK ACADEMY OF SCIENCES 



of the sciaenoids have a large natatory bladder, very thick, provided with 

 very strong muscles, but the bladder has no communication either with 

 the intestinal canal, or with the exterior generally." This represents all 

 that was actually known up to the time of Cuvier concerning the mechan- 

 ism of the sound-producing organs. It was evidently thought by Cuvier 

 that the air-bladder and attending muscles were of some importance in 

 producing this phenomenon. 



Somewhat later (1860), Holbrook stated that "frequent examinations 

 of the structure and the arrangement of the air-bladders, as well as obser- 

 vations on the living animal just taken from the water, when the sound is 

 at intervals still continued, have satisfied me that it is made in the air-bladder 

 itself; that the vibrations are produced by the air being forced by strong 

 muscular contraction through a large opening, from one large cavity, that 

 of the air-bladder, to another, that of the cavity of the lateral horn; and 

 if the hands are placed on the sides of the animal, vibrations will be felt 

 in the lateral horn, corresponding wdth each sound." 



It was not until Dufosse published his memoir on the sounds and noises 

 produced by the fishes of Europe, in 1874, that we had any physiological 

 explanation of the phenomenon in the scisenoid fishes which is based on 

 actual experiments. In 1864, Moreau published the results of his experi- 

 ments on the "grunting" mechanism in the Triglidse, a process, however, 

 which is entirely different from the "drumming" of the Sciaenidfe, and 

 should not be confounded with it. With regard to the sounds produced 

 by certain muscles Dufosse says, 



Le phenomene physiologique connu generalement sous le nom de trepidation 

 ou tremulation musculaire, et que WoUaston a assimil^, avec raison, a un mouvement 

 de vibration, n'a pour ainsi dire ete observe que chez rHomme, et n'a jamais ete 

 le sujet d'une etude approfondie, soit au point de vue biologique, soit au point de 

 vue la physique proprement dite, quelques physiologistes pensent meme encore 

 que ce mouvement assez rapide pour produire un leger bruit, designe sous le nom 

 de bruit de rotation par Laennec et sous celui de bruit de contraction des muscles par 

 d'autres auteurs, est trop faible par lui-meme et trop peu important par ses effets 

 pour devenir jamais d'un certain interet en physiologie generale. 



This is a concise statement of what was known concerning the physiology of 

 this noise at the time when Dufosse wrote his memoir. Dufosse divided 

 his work into two propositions, viz: 



1. Quelques muscles de certains poissons bruyants deviennent en se contractant 



susceptibles d'un mouvement de vibration: 



2. Ce mouvement est le principe des sons que font entendre ces animaux. 



To prove these propositions, Dufoss^ made two physiological expcri- 



