No. I.] THE VERTEBRATE EAR. 283 



The Organ of Cortt, or the Mammalian Cochlear Organ. 



The development of the cochlear tube precedes that of the 

 ultimate cochlear organ by a long space of time. The continu- 

 ous but very gradual differentiation of the cochlear organ in the 

 vertebrate series above the fishes would, from the morphological 

 standpoint, argue a gradual increase in the physiological func- 

 tion, and the rapid acquisition of length by the canal, as well as 

 the wonderful complication of structure in the sense organ con- 

 tained, certainly points to an important functional activity ; but 

 when we attempt to determine the character of the function and 

 its mechanical execution, we meet with almost insuperable diffi- 

 culties. As I have indicated, none of the theories yet put for- 

 ward are sufficient to explain the facts, and every one of them 

 is antagonistic to some important morphological relation, which 

 must invalidate the arguments in greater or less degree. 



The ability which many animals with a simple type of coch- 

 lear organ display in appreciation of the value of the musical 

 quality of sounds, noises, tones, and their remarkable facility in 

 perceiving the minutest variations in the intensity, pitch, timbre, 

 and other tonal qualities, render any arguments as to the 

 increase of physiological activity, based on a greater complexity 

 in structure of the cochlear organ, not only valueless, but mis- 

 leading. Our knowledge, especially of the function of this part 

 and the nerve-end relations, is very imperfect — more so, I fear, 

 than most students appreciate ; but I do think that it is a sub- 

 ject which proper experimentation may and will overcome in 

 the, let us hope, near future. Much depends upon our ability 

 to decide definitely what the function of the canal sense organs 

 is, for on the determination of this problem depends the solu- 

 tion of all the physiological problems of the internal ear. The 

 direct connection of the tympanic conducting apparatus to the 

 perilymphatic spaces which surround the saccular chamber or 

 its derivatives in varying degree in the different groups of verte- 

 brates, is a character of considerable physiological importance, 

 but not deserving of such weight as Hasse and Meyer are 

 inclined to attribute to it. For although in the Amphibia the 

 whole saccular perilymphatic chamber is directly connected 

 with the columella, and in reptiles the sacculus and the base 

 of the cochlea are thus connected, and in the birds and mam- 



