No. I.] THE VERTEBRATE EAR. 261 



" Now Corti's fibres (pillars) are wound round and covered 

 over with a multitude of very delicate, frail formations, — fibres 

 and cells of various kinds, partly the finest nerve terminal fibres 

 with appended cells, and partly fibres of ligamentous tissue, 

 which appear to serve as a support for fixing and suspending 

 the nerve formations. They are grouped, like a pad of soft 

 cells, on each side of and within Corti's arches. The most 

 important of them appear to be cells which are furnished with 

 hairs, precisely resembling the ciliated cells in the ampullae and 

 utriculus. They appear to be directly connected by fine vari- 

 cose nerve fibres, and constitute the most constant part of the 

 cochlean formations ; for with birds and reptiles, where the 

 structure of the cochlea is much simpler, and even Corti's 

 arches are absent, these little ciliated cells are always to be 

 found, and their hairs are so placed as to strike against Corti's 

 membrane during the vibration of the membrana basilaris." 



" The essential result of our description of the ear may con- 

 sequently be said to consist in having found the terminations of 

 the auditory nerves everywhere connected with a peculiar aux- 

 iliary apparatus, partly elastic, partly firm, which may be put in 

 sympathetic vibration, under the influence of external vibration, 

 and will then probably agitate and excite the mass of nerves. 

 Now it was shown . . . that the process of sympathetic vibra- 

 tion was observed to differ according as the bodies put into 

 sympathetic vibration were such as, when once put in motion, 

 continued to sound for a long time or soon lost their motion. 

 Bodies which, like tuning-forks, go on sounding for a long time, 

 are susceptible of sympathetic vibration in a high degree, not- 

 withstanding the difficulty of putting their mass in motion, 

 because they admit of a long accumulation of impulses, in them- 

 selves minute, produced in them by each separate vibration of 

 the exciting tone. But, precisely for this reason, there must be 

 the exactest agreement between the pitches of the proper tone 

 of the fork and of the exciting tone, because otherwise subse- 

 quent impulses, given by the motion of the air, could not con- 

 stantly recur in the same phase of vibration and thus be suitable 

 for increasing the subsequent effect of the preceding impulses. 

 On the other hand, if we take bodies for which the tone rapidly 

 dies away, such as stretched membranes, or thin, light strings, 

 we find that they are not only susceptible of sympathetic vibra- 



