ti68 THE EAR. 



have a common function, namely, the appreciation of mass-movement. Beard l 

 had already argued in favour of the parts of the internal ear and the organs of 

 the lateral line being phylogenetically related. According to these somewhat 

 speculative views, when animals became air-breathers, a part of the ear, the 

 papilla acustica basilaris, was gradually evolved for the perception of the 

 delicate vibrations of sound, while even in the higher vertebrates the nerve- 

 endings in the saccule and utricle may still have to do with only the percep- 

 tion of mass movements. While it may be that fishes are deaf, it is difficult 

 to believe that hearing is associated in the higher animals solely with the 

 cochlea. In certain fishes there are connections in the form of ossicles between 

 the air-bladder and the acoustic labyrinth, 2 and in these it is possible the 

 air-bladder may act as a resonator, as Johannes Miiller thought. 3 In the higher 

 forms of vertebrates the intricate relations between the membrana tympani 

 and the saccule and utricle by the chain of ossicles indicates that these 

 sacs, while they may retain their primitive function of appreciating mass 

 movements, are also the recipients of those more delicate movements caused by 

 sound-waves impinging on the membrane. 



The Cochlea. 



It is remarkable that some of the older anatomists conjectured, long 

 before the discovery of the organ of Corti, that this part of the internal ear 

 was in some way analogous to a musical instrument, having wires of vary- 

 ing lengths tuned to tones of different pitch. 4 Helmholtz, however, was 

 the first to put forth a theory as to its mode of action, and whether 

 this theory be accepted or not, all discussions of the subject must take 

 the work of Helmholtz as a starting point. 5 Let us inquire, in the first 

 place, what the ear is capable of doing. "We can hear musical tones and 

 noises, we have a peculiar auditory sensation to which we give the name 

 of beats, and we have the power of analysing a musical tone into its 

 components. These are sensations capable of being tested by direct 

 experiment. 



For this purpose, the inquirer should be furnished with — (1) A set of 

 forks ranging in pitch from 128 to 1024 vibs. per second, say ut 2 , ut 3 , soI 3 , 

 ut*, miy soZ 4 , ti v ut 5 ; (2) forks corresponding to re 3 , mi 3 , mip, fa 3 , la 3 , 

 lap ; (3) a set of resonators, as devised by Helmholtz, corresponding to those 

 forks ; (4) the manometric analyser, for the series of forks enumerated in (1) ; 

 (5) a double syren ; (6) a set of steel cylindrical bars, for tones of very high 

 pitch ; and (7) a few rectangular brass clips, capable of sliding freely on any of 

 the forks, with a tightening screw. 6 



Pitch.— As determined by the syren, a sensation of musical tone 

 begins with about 30 vibs. per second. It is, however, difficult to 

 appreciate the pitch of musical intervals in the lower ranges, and it 

 is only with about 40 vibs. per second that pitches are clearly 



1 Zool. Am., Leipzig, 1884, Bd. vii. S. 140. 



3 Owen, " Comparative Anatomy," vol. i. p. 342. 



3 "Physiology," vol. ii. p. 1245. 



4 "Anatomy," by John and Charles Bell, 1816, vol. iii. 



5 Rayleigh, op. tit., vol. ii. p. 432. 



6 The best acoustical apparatus is supplied by Dr. Rudolf Kbnig, Quai d'Anjou, Paris. 

 An excellent set of apparatus, consisting of bellows, overtone apparatus, difference tone 

 apparatus, apparatus for beats, and fine rich reed tones, is made by Appunn of Hannau, 

 near Frankfort. Appunn's apparatus consists almost entirely of reeds, with appropriate 

 resonators. It is described in "Sprache und Ohr, " by Oskar Wolf, Braunschweig, 1871, 

 S. 15. See also M'Kendrick, Proc. Boy. Soc. Edin., 1873-74. 





