30 TAILS 



requires — with a definition, we stumble on a key, 

 at the very threshold, which opens the door. For 

 there is no definition of a tail ; it is not, in its 

 nature, anything at all. When an animal's fore-legs 

 are fitted on to its backbone at the proper dis- 

 tance from the hind-legs, if any of the backbone 

 remains over, we call it a tail. But it has no pur- 

 pose ; it is a mere surplus, which a tailor (the pun 

 is unavoidable) would have trimmed off. And, lo ! 

 in this very negativeness lies the whole secret of the 

 multifarious positiveness of tails. For the absence 

 of special purpose is the chance of general usefulness. 

 The ear must fulfil its purpose or fail entirely, for it 

 can do nothing else. Eyes, nose and mouth, hands 

 and feet, all have their duties ; the tail is the un- 

 employed. And if we allow that life has had any 

 hand in the shaping of its own destiny, then the 

 ingenuity of the devices for turning the useless 

 member to account affords one of the most exhilara- 

 ting subjects of contemplation in the whole panorama 

 of Nature. The fishes fitted it up at once as a twin- 

 propeller, with results so satisfactory that the whale 

 and the porpoise, coming long after, adopted the 

 invention. And be it noted that these last and their 

 kin are now the only ocean-going mammals in the 

 world. The whole tribe of paddle-steamers, such 

 as seals and walruses and dugongs, are only coasters. 

 Among those beasts that would live on the dry 

 land, the primitive kangaroo could think of nothing 

 better to do with his tail than to make a stool of it. 



