142 DARWINISM AND THE PROBLEMS OF LIFE 



to the lizard, has also endowed it with the faculty of 

 creating a fresh one if it is lost. Three weeks after 

 the removal of the tail there is a leathery prominence at 

 the wound. This continues to grow, and forms a new 

 tail, which is so much like the old one that it takes an 

 expert eye to see the difference. However, the new 

 one never becomes as long as the old one, and it may 

 take two years to become perfectly similar to the old 

 one in colour and shape. 



The faculty of re-making lost limbs is called 

 regeneration, and it forms a fitting transition from the 

 reptiles to the amphibia. These have an even greater 

 power of regeneration than the reptiles. It is true that 

 a frog's legs do not grow again if they have been cut 

 off, as many peasants believe, when they throw the poor 

 creatures into the water again after amputating them ; 

 but the tailed relative of the frog, the newt, can 

 reproduce a great part of the body. Its legs grow- 

 again when they have been cut off, the skin always 

 heals, and even a new eye is formed when one has been 

 torn out. The newts are exposed to the attacks of a 

 large number of enemies ; fishes, birds, and their own 

 relations, are continually after them, but it is especially 

 the large water-beetles that often clip off their legs with 

 their sharp jaws, or bite off an eye. Hence the power 

 of regeneration is confined to parts of the body which 

 are apt to be frequently lost in this way ; this happens 

 especially to the newt's legs. The lizards are not 

 easily grasped by the leg by their enemies, and so this 

 has not the power to reproduce itself, as their tail has. 

 A poisonous snake is never seized by the tail, because 



