PARTS OF ANIMALS, II. x.-xii. 



(Taste, in fact, is itself, as it were, a sort of touch.) 

 The duality is plain, however, even with this sense, 

 for it is seen to be divided." With the other senses, 

 the organ is more evidently parted into two : there 

 are two ears and tΛvo eyes, and two passages for the 

 nostrils in the nose. The sense of smell, if it had 

 been other^vise placed — separated into two, that is, 

 like the sense of hearing — would not have been 

 able to perform its proper function ; nor would 

 that part of the body in which it is situated, since 

 in animals which have nostrils, the sensation of 

 smell is effected by means of inspiration, and this 

 part is at the front and in the middle. This is 

 why Nature has brought the nostrils together in a 

 straight line and made them the central of the three 

 sense-organs in the head, located where the motion 

 of in-breathing takes place. 



In the other animals as Avell as in man these sense- : 

 organs are very satisfactorily arranged as required 

 by the peculiar nature of each animal. XI. For 

 instance, the quadrupeds have ears that stand out free 

 from the head, and they are higher than the eyes — 

 or appear to be, although this is not really so : it is 

 an illusion due to the fact that these animals are not 

 upright but stand on all fours. And as they are 

 usually in this posture when in motion, it is useful for 

 them to have their ears well up in the air, and also 

 movable : this enables them to be turned round and 

 oick up sounds better from all directions. 



XII. Birds have the auditory passages only, 

 o\nng to the hardness of their skin, and because 

 they have feathers instead of hair, Λvhich means that 

 they have not got the right material for forming 

 ears. The same argument apphes to those oviparous 



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