No. I.] THE VERTEBRATE EAR. 277 



transmitted through the investing cranial bones. Not that it 

 is denied that such transmission of vibrations through the 

 cranial bones may take place, but there is neither physical 

 nor morphological basis for the conclusion that the two parts 

 of the ear are not subject to all vibrations affecting the ear from 

 whatever source, in quite equal degree. It is certainly not made 

 clear on physical grounds by Meyer nor his predecessors in this 

 view, Hasse, Lucae, Mach, Politzer, and others, nor by his suc- 

 cessors, more especially and recently Hensen, how the vibra- 

 tions affecting the cranial bones are transmitted to the utricular 

 section of the canal complex more than to the saccular section, 

 and there is no mention of anatomical arrangement of the parts 

 adequate to the work of insulating the cochlea or any other part 

 of the saccular region from these vibrations. So far as our 

 knowledge extends at the present day, the only conditions 

 affecting the activity of the sense organs is the greater or less 

 perfection or specialization of the sense organs themselves, in 

 the direction of greater or less sensitiveness to stimuli, differing 

 in pitch, intensity, and other qualities, if such there are. 



As Hasse had already shown, and as Meyer notes as an inter- 

 esting condition, the perilymphatic spaces of Chelonians is so 

 large and extensive that any vibration whatsoever, arriving at 

 any part of the surface of this sac, would be transmitted equally 

 well to all parts of the internal ear. 



From a general standpoint, it is evident that there is no pecul- 

 iar or special kind of wave motion (vibration, undulation) which 

 alone is entitled to be called sound wave ; for all so-called sound 

 waves may (produce) give rise to sensations otJier than those of 

 hearing. And those vibrations of the atmosphere which serve 

 to cause the sensations of hearing in the ears of one individual 

 may entirely fail of that effect in the ears of another. We have 

 a so-called musical scale within whose limits all possible sounds 

 must fall, as far as concerns their pitch ; but since some ears 

 are not sensitive to low notes, and others deaf to high-pitched 

 notes, it follows that there is no rigid auditory scale, and con- 

 sequently no sharp line -of demarcation between genuine audi- 

 tory and tactile stimuli when caused by disturbances in the 

 supernatant fluid of the sense organs of the ear on the one 

 hand, and of the surface of the skin on the other. 



All sonnd waves are taken up from the endolymphatic liquid ; 



