SENSES, INSTINCTS, AND INTELLIGENCE 331 



with a large surface of olfactory membrane spread over 

 twisted turbinal or scroll bones in the nasal chamber, 

 and the narrow horn-encased nostrils of birds, with very 

 little hint of turbinal bones. In some birds, like pelicans 

 and cormorant, the nostrils of the adult are closed up. 

 The Kiwi or Apteryx is the only bird with the nostrils at 

 the tip of the bill ; in all other birds they lie far back at 

 the base of the bill. 



It is by sight not by smell that the eagles or vultures 

 gather to the carcass. One bird sees the dead or dying 

 animal and descends on it, the descent of the first is seen 

 by a second, and so the news travels from one aerial outlook 

 to another. The nerve-endings on the olfactory membrane 

 are contact-receptors, that is to say, odoriferous particles, 

 either in a solid or a vaporous state, must land on the 

 moist surface of the membrane. The fibres from the 

 nerve-endings combine to form the olfactory nerve leading 

 into the front of the cerebral hemispheres of the brain. 



In connection with the relative unimportance of the sense 

 of smell in most birds, it is interesting to notice that birds 

 produce little odour. Apart from the occasional presence 

 of small glands in the vicinity of the ear-opening, birds 

 have only one skin-gland — the preen-gland at the root of 

 the tail, and its secretion has little odour to us. Thus 

 in birds recognition is mainly by sight, whereas in mammals 

 odour helps not a little. The cleverness dogs show in 

 detecting a bird's presence by scent shows that birds have 

 their odours, but the point is that these are delicate and do 

 not seem to be of much importance in the relations of birds 

 to one another. An interesting detail which some natura- 

 lists vouch for is that the odour of some birds, e.g. partridge, 

 is reduced to a minimum when the bird is brooding. 



Sense of Touch. — Most of the bird's body is obviously 

 covered with feathers, horn ensheaths the jaws, scales 

 invest the toes, and the fingers are hidden, so that there is 

 relatively little opportunity for the development of tactility. 

 There are nerve-endings, however, at the base of many of 

 the feathers, the tip of the tongue is often a touch-organ, 



