230 THE MEANING OF EVOLUTION 



actly tlie reverse plan. Using" his tremendous head as 

 a battering- ram in lighting, and using his enormous 

 tusks l)oth in battle and in uprooting young trees, a 

 lengthened neck is absolutely out of the question. 

 Furthermore his front teeth have grown so prodi- 

 giously that they would interfere with his getting his 

 mouth to water. Accordingly, his nose has length- 

 ened its tip until it reaches the level of his feet, and 

 this nose becomes to him the main organ of gras[^ 

 and of touch. To drink, its end is inserted in the pool 

 and water is drawn up the nostril. If the animal were 

 to attempt to draw it all the way back into his throat, 

 it would inevitably strangle him by getting into his 

 windpipe. Accordingly, when the nose is well filled 

 with water, the tip of it is inserted in his mouth, and 

 the water discharged by a quick puff. The horse has 

 taken a method intermediate between these. It had 

 moderately lengthened both neck and head in order 

 to get to the ground with its nipping teeth, and thus 

 to gather the grasses which serve as its principal food. 

 The mammalian teeth, while of four kinds, really 

 in most animals serve but two purposes. The front 

 teeth consist of the incisors and canines, and are used 

 for biting. The hind teeth, consisting of premolars 

 and molars, are used for grinding. In the horse, the 

 jaw has lengthened between these two sets, carrying 

 the biting teeth far forward of the molars. It is this 



