PARTS OF ANIMALS, III. ii.-iii. 



bodies consists of earthy matter ; so if we consider 

 the majority of cases, we can say that there is most 

 earthy matter in the biggest animals.) At any rate, 

 in the larger animals there is present a surplus of 

 this corporeal or earthy matter, produced as a 

 residue, and this Nature makes use of and turns to 

 advantage to provide them with means of defence. 

 That portion of it which by necessity courses upwards 

 she allots to form teeth and tusks in some animals, 

 and to form horns in others. And we can see from 

 this why no horned animal has incisor teeth in both 

 jaws, but only in the bottom jaw. Nature has 

 taken away from the teeth to add to the horns ; 

 so that the nourishment which would normally be 

 supplied to the upper teeth is here used to grow the 

 horns. Why is it, then, that female deer, although 

 they have no horns, are no better off for teeth than 

 the male deer ? The answer is : Both of them are, 

 by nature, horned animals ; but the females have 

 lost their horns because they would be not only 

 useless but dangerous. The horns are indeed of no 

 more use to the males, but they are less dangerous 

 because the males are stronger. 



Thus in some animals this " part "^ of the body 

 is secreted for the formation of horns ; in others, 

 however, it causes a general increase in the size of 

 the teeth, and in others again it produces tusks, 

 which are like horns springing out of the jaws 

 instead of the head. 



We have now dealt with the " parts " that apper- 

 tain to the head. 



III. The place of the neck, when there is one, is Of the 

 below the head. I say " when there is one," because oesopha^'us 

 only those animals have this part which also have 



225 



