XII 



WHY DO ANIMALS BECOME EXTINCT? 



" And Sullcm after Saltan with his Pomp 

 Abode his destined Hour and went his way." 



It is often asked " why do animals become ex- 

 tinct ? " but the question is one to which it is 

 impossible to give a comprehensive and satis- 

 factory reply ; this chapter does not pretend 

 to do so, merely to present a few aspects of 

 this complicated, many-sided problem. 



In very many cases it may be said that act- 

 ual extermination has not taken place, but 

 that in the course of evolution one species has 

 passed into another ; species may have been 

 lost, but the race, or phylum endures, just as 

 in the growth of a tree, the twigs and branches 

 of the sapling disappear, while the tree, as a 

 whole, gi'ows onward and upAvard. This is 

 what we see in the horse, which is the living 

 representative of an unbroken line reaching 



220 



