THE CLUFEOID CRANIUM AND THE SWIMBLADDER 443 



He observed the lateral recess of the skull (which has been almost 

 overlooked by later investigators) and its relation to the mem- 

 branous labyrinth internally, and to the lateral line system 

 (canaux excreteurs) externally. That this unusual relationship 

 might have a functional significance, he evidently recognized, 

 though the theory which he proposed is hardly consistent with 

 modern physiological knowledge. 



Breschet's conception of the perilabyrinthine spaces was re- 

 markably accurate, considering the crude technical methods of 

 investigation available in his time. He describes the ear as 

 composed of tissue ''ni absolument membraneux, ni absolument 

 cartilagineux," fragile, a little elastic, and of the softness of 

 rubber. He speaks of two 'commissures,' made up of the same 

 tissue as the rest of the organ which hold the two ears together. 

 One of these 'commissures' he describes as passing above the 

 brain and connecting the utricular sinuses of the opposite sides; 

 the other ' commissure' is the structure that Weber described as 

 an endolymphatic connection between the two utriculi. Bres- 

 chet, however, describes these commissures as not hollow like 

 the membranous labyrinth, but composed of a 'tissu foliace,' 

 or a membrane 'pliee ou roulee,' which is only a thickening of 

 the tissues of the vestibule. He says: "La commissure in- 

 ferieure n'offre point de veritable canal dans son interieur, pas 



plus que la commissure superieure La substance de 



la commissure s'indentifie avec les parois du vestibule, et ne 

 doit etre consideree que comme une expansion membraneuse de 

 ces dernieres." Modern technique proves Breschet to have 

 been essentially correct in his conception of these structures. 

 Nevertheless, certain investigators long after his time persisted 

 in considering these structures as endolymphatic canals. 



Breschet describes what he called an 'accessory bulb' attached 

 laterally to the utriculus under the ampullae of the horizontal 

 and anterior semicircular canals. He describes the utriculus as 

 merely resting on the anterior capsule, thereby denying the 

 existence of Weber's vestibular diverticulum. 



Hasse ('73) investigated the ear and swimbladder diverticulum 

 in Clupea alosa and Clupea harengus. He carries Breschet's 



