264 Anmial Life and Intelligence. 



acute. The form and movements of the external ear also 

 enable many of the mammalia to collect and attend to 

 sounds from special directions. The mammalia possess 

 also the power of tone-discrimination, as is shown by the 

 fact that our domesticated animals recognize different 

 modulations of the human voice, and that wild creatures 

 distinguish tones or noises of different quality. A New- 

 foundland dog, possessed by a friend of mine, always 

 howled when the tenor D was struck on the piano, or sung. 

 And Theophile Gautier reports that one of his cats could 

 not endure the note G, and always put a reproving and 

 silencing paw on the mouth of any one who sang it. 



In birds the sense of hearing is not only very sensitive, 

 but the power of discrimination is exceedingly delicate. 

 No one who has watched a thrush listening for worms can 

 doubt that her ear is highly sensitive. The astonishing 

 accuracy with which many birds imitate, not only the song 

 of other birds, but such unwonted sounds as the clink of 

 glasses or the ring of quoits, shows that the delicacy in 

 discrimination has reached a high level of development. 

 In birds, however, the cochlear canal has not the same 

 development that it has in mammals, and there are no 

 arched rods — no organs of Corti. 



Nothing special is to be noted concerning the sense of 

 hearing in the reptiles, amphibia, and fishes. In all (with 

 the exception of the lowly lancelet) the auditory organ is 

 developed. We shall, however, presently see reason to 

 question whether the possession of an '' auditory organ," 

 with well-developed semicircular canals, necessarily indicates 

 the power of hearing. And Mr. Bateson's recent experi- 

 ments at Plymouth* seem to indicate that fishes are not so 

 sensitive in this respect as anglers f are wont to believe. 

 " The sound made by pebbles rattling inside an opaque 

 glass tube does not attract or alarm pollack ; neither are 

 they affected by the sharp sound made by letting a hanging 



* Journal of Marine Biological Association, New Series, vol. i. No. 3, p. 251. 

 t Of course, anglers will say that what may be true for pollack and other 

 coarse and vulgar sea-fish does not apply to King Salmon or Prince Trout, 



