ORGANS OF TASTE AND TOUCH. 157 



filled with fluid. These are named the Semicircular Canals, of 

 which, in this bird, the largest is the posterior, or superior, f^ 

 and has a vertical position ; the anterior, g, is next in size, 

 and in crossing the middle one, h, communicates with it. At 

 their entrance into the vestibule these canals have an enlarged 

 space, named the Ampulla. In man and the mammalia, there 

 is moreover a large spiral cavity divided longitudinally by a 

 partition into two cavities, which communicate at the tip ; but 

 in the Buzzard all that represents this part is a small oblong 

 space, having internally two cartilaginous cylinders, which 

 divide it into two cells, one of which opens into the vestibule, 

 while the other communicates with the membrane closing the 

 foramen rotundum of the tympanum. 



As in the eye the retina or expansion of the optic nerve re- 

 ceives and conveys to the brain the impression of light ; so the 

 delicate fibrils of the auditory nerve distributed over the inner 

 surface of the internal cavity of the ear, receive and impart to 

 the brain the impression of sounds. Bodies which emit sound 

 by being thrown into a state of vibration, communicate to the 

 air impressions causing a peculiar motion of its particles. The 

 air thus acted on is admitted by the external aperture of the 

 ear, and strikes against the membrane of the tympanum, the 

 slender bone attached to which communicates the impression 

 to the internal ear, in which the extremities of the auditory 

 nerve receive it, and convey it to the brain. But of the man- 

 ner in which the perception of sounds is effected we know 

 very little. Fig. 3 represents the external aperture of the ear 

 in the Peregrine Falcon. 



Having thus partially examined the organs of sight, smell, 

 and hearing, we may now" advert to those of Taste and Touch. 

 In man and the mammalia generally, the tongue is the Organ 

 of Taste ; and in birds it must be so too ; but they seem to pos- 

 sess the faculty only in a very imperfect degree. As birds do 

 not masticate their food, but the moment the object or morsel 

 is seized, swallow it entire, their tongue is more an organ of 

 prehension than of taste, and is generally more or less sheathed 



