GENERATION OF ANIMALS, V. vi.-vn. 



Further, the tongues of animals differ : those of 

 the simple-coloured " animals, those of the variegated 

 ones, and those of the ones which, though simple- 

 coloured yet differ among themselves (as, e.g., dark 

 and white)— the tongues of these are all different. 

 The reason is that which has been stated already, 

 viz., that the skins of variegated animals are varie- 

 gated, the skins of white-haired ones are white and 

 of dark ones dark. The tongue we should look upon 

 as being, as it were, one of the external parts of 

 the body, comparable, e.g., ^^ith the hand or foot, dis- 

 regardinof the fact that it is being covered in bv the 

 mouth. So that, as the skin of the variegated animals 

 is not single-coloured, this will be the reason respon- 

 sible for the skin on the tongue as well. 



Some birds and some >\-ild quadrupeds change their Seasonal 

 colour according to the seasons of the year. The c^fo^ "'^ 

 reason is that, just as human beings change according 

 to their age, so these change according to the seasons, 

 because this constitutes a greater difference so far as 

 they are concerned than the change according to age. 



Speaking generally, the more omnivorous animals Effect of 

 are more variegated, as we should expect (for in- co^om! 

 stance, bees are more single-coloured than hornets 

 and wasps), for of course if the various sorts of 

 nourishment they take are the causes of the change, 

 we shall expect to find that variegated kinds of 

 nourishment make the movements which the nourish- 

 ment undergoes and the residues which result from 

 it more variegated, and it is out of the residues that 

 hair, feathers, and skin are formed. 



This concludes our account of the various colours, 

 and the various kinds of hair. 



With regard to the voice : some animals have a VII 



Voice. 

 54,1 



