ON THE ANATOMY OF FISHES. 
273 
From the date of the publication of Weber’s memoir until the appearance of 
Hasse’s paper (18) in 1873, the majority of writers on this subject have more or less 
explicitly accepted Weber’s views with but little or no qualification, and the term 
“ auditory,” as applied to the ossicles, still lingers as an interesting survival of the 
notion which he entertained of their function. But in addition to tliose who, like 
Weber, apparently regard the Weberian ossicles as related solely to audition, there 
are others who, while assigning a very different primary function to those structures, 
are not altogether prepared entirely to exclude the possibility that they may still be, 
in .some subordinate degree, accessory to the function of hearing, and among such 
writers must be included Hasse — the first opponent of Weber’s theory — and 
Ramsay Wright. 
Apart from the a 'priori probability that the existence of an anatomical connection 
between the air-bladder and the internal ear, is to render the former a physiological 
accessory to audition, and the apparent analogy between the Weberian ossicles and 
the auditory ossicles of the higher Vertebrata, there is but little to be said in favour of 
Weber’s view, and even this argument may be used in quite another way and with 
equal force, for it is at least as likely that the Weberian ossicles are related to some 
function of the air-bladder as that they are subsidiary to any function of the internal 
ear. On the other hand, thei’e are many and weighty reasons for the belief that 
Weber’s theory is absolutely untenable, and of these we may direct attention to the 
following : — 
O 
(1.) The imperfections of the air-bladder and the Weberian mechanism considered as 
structures accessory to audition. The gravest objections to the theory certainly come 
under this head. It may be objected — 
(a.) That sound vibrations pass with great difficulty from water to air, and hence, 
if such vibrations are to pass at all from the external medium to the gases contained 
within the air-bladder, the transmission must be accompanied by a considerable loss of 
intensity, and the effect upon the latter can be but slight. The intervention of a solid 
medium between the external surface of the body and the fluids of the internal ear, 
such as may be found in the bones of the skull, would afford a far better channel for 
sound conduction than a membranous air-containing sac.* Moreover, although this 
objection does not apply to the Siluridae with lateral cutaneous areas, the sound waves 
in passing from the exterior to the gases of the air-bladder must be greatly retarded 
in m.ost Ostariophyseae by having to traverse, not only the lateral muscles of the body 
wall, but also the air and fluid infiltrated spaces or organs of varying densities by 
which the bladder is surrounded. 
(6.) Assuming, in spite of this difficulty, that the air in the air-bladder can be 
thrown into vibration, it may yet be objected that in many Siluridae the walls of that 
* The minute size of the external auditory meatus in some aquatic mammalia (Cetacea) suggests that 
even in these animals the sound waves, which are effective as auditory stimuli, must traverse the cranial 
bones. 
2 N 
MDCCCXCIII. — B. 
