AND THEIR FUNCTIONS. 135 



Chalcidice. He also says that in Astyra and Antandria are 

 two rivers, of which one makes sheep white and the other 

 makes them black. The river Scammander, he says, seems 

 to make them light brown, and on this account some say 

 that Homer called this river Xanthus.* 



The hare is the only animal, Aristotle says, which has 

 hair within its cheeks and on the under sides of its feet.t 

 It is true that the hare has hairs on the insides of its mouth 

 and beneath its feet, but so also have other rodents, like 

 the rabbit and squirrel, and, among animals not known to 

 Aristotle, the polar bear, in particular, has hairs beneath 

 its feet. 



e. Feathers, Scutes, and Scales. Aristotle s views on 

 these anhomoeomeria are closely connected with his views 

 on the analogy and, it may be said, homology of the parts of 

 animals, and will be more suitably considered from this 

 point of view in Chapter xv. 



He mentions the chief parts of a bird s feather, viz., the 

 shaft and barbs, and distinguishes it from the wing of an 

 insect, which appears to be of the nature of a feather, being 

 a skin-like membrane which, because of its dryness, becomes 

 detached from the surface of the body, t 



Aristotle says correctly that many birds change colour 

 with the seasons in such a way that an observer, if in 

 experienced, is deceived thereby, but he does not correctly 

 explain the occurrence of albino ravens, sparrows, and 

 swallows, for he says that they become white when the cold 

 increases. He says also that the crane, which is ash- 

 coloured, darkens with age and is the only bird whose 

 plumage changes with age.|| This is not correct, for, 

 besides the great changes which take place in the plumage 

 of many birds, from the young to the adult stage, changes 

 in brilliancy or depth of colour may be seen, after successive 

 moults, in many birds. In wild linnets, for instance, the rose- 

 coloured parts are larger and more brilliant in the older birds. 



The looseness and thin nature of the barbs of the 

 feathers of the ostrich were known to Aristotle, for he says 

 that they are of the nature of hair and useless for flight.^! 



Oviparous quadrupeds, he says, have scutes.** This 

 statement is incomplete, for some, like the frog and water 



* H. A. iii. c. 10, s. 12. \ Ibid. iii. c. 10, s. 13. 



| P. A. iv. c. 6, 6826. H. A. iii. c. 10, s. 11. 



li Ibid. 1i P. A. iv. c. 13, 6976. 



** H. A. iii. c. 10, a. 1. 



