No. I.] THE VERTEBRATE EAR. 28 1 



des intervalles musicaux et du timbre des sons. II serait par 

 consequent interessant d'examiner si les Poissons sont sensibles 

 au bruit seulement, ou si ces Animaux sont capables de distin- 

 guer les differences de ton et de timbre ; niais je connais anain 

 fait qui nous pennette de trancJier la question " [italics mine]. 



The field for experiment is as open to-day as when Milne- 

 Edwards reviewed the subject. 



Although Exner believed that the organ of Corti was capable 

 of perceiving not only tones but all other noises as well, Hensen 

 held to the doctrine advanced by Helmholtz, according to which 

 the cochlear organ was capable of perceiving tones only. As to 

 Topler's experiments with the electric spark, which gives only 

 a single, short, sharp impulse to the air, or it snaps, as we say, 

 Helmholtz concluded that such a snap could not possibly give 

 rise to an irritation of the cochlear apparatus ; indeed, a series 

 of such snaps would not give rise to a tone unless they followed 

 each other with a considerable degree of rapidity. But it is 

 found that an increase in the rate at which the electric sparks 

 followed each other caused a like elevation of the pitch of the 

 sound, and as Hensen truly says, "Diese Erfahrung wiirde 

 entweder denn doch auf die Betheiligung des klangempfindenden 

 Apparates deuten, oder sie wiirde auf einen zweiten Apparat, 

 der gleichfalls Hohen — und Tiefenempfindung hervorzurufen 

 vermag, zu beziehen sein. Zwei verschiedene Endapparate von 

 Sinnesnerven, welche beide die gleiche Empfindung der Tonhohe 

 hervorrufen, stimmen nicht mit unseren Kenntnissen von den 

 Sinnesorganen iiberein und widersprechen den ' Gesetzen der 

 specifischen Sinnesenergie.' " Hensen then proceeds to explain 

 how the basilar membrane fibres might take part in the percep- 

 tion of such snaps. After what I have said in the morphological 

 part, it needs no special explanation to make clear that there is 

 no such sharp and fundamental separation of the auditory sense 

 organs, as regards their functions, as Hensen here assumes. 



Whatever differences in the powers of tone perception there 

 may be between the various sense organs of the ear, there can 

 only be differences of degree, and not of kind. In my mind 

 there exists no doubt that the cochlear organs perceive all kinds 

 of sounds. 



When Hensen asserts that the perception of the pitch of tones 

 does not necessarily immediately concern the cochlear organ 



