THE WONDER OF LIFE 563 



newt should have its eye gouged out ? To this Weismann 

 answers that newts fight furiously, at any rate at the 

 breeding season, and often injure one another ; and that 

 the larvse of the large water-beetle (Dytiscus marginalis) 

 often attack newts just behind the head. Moreover the 

 water-snail Limneea, though usually vegetarian, is some- 

 times found killing a newt, getting upon its back and 

 fihng the skin with its radula. It is probable that 

 a more complete knowledge of the hfe of Amphibians 

 would show that serious injury to the eye is not a rare 

 casualty. 



A very interesting case is given by Bordage. In locusts 

 and related insects, the loss of one of the first two pairs of 

 legs is followed by regeneration. On the other hand, the 

 posterior or third pair of legs, which are of great importance 

 in jumping, are not regenerated. Now why should this 

 be, that the less important may be re-grown, while the more 

 important are not ? This seems quite inconsistent with 

 Lessona's law. But Bordage points out that the loss of 

 the posterior legs almost prevents moulting, leaves the 

 locusts exposed to great danger, and, furthermore, prevents 

 breeding. Perhaps therefore the case is covered by the 

 corollary to Lessona's law — ' provided the injury be not 

 fatal '. Nor can one conceive how organic provision 

 could be made for an injury which prevents breeding. The 

 prevention of breeding is a full-stop to the evolution of an 

 adaptive feature of any kind. 



Some of the cases of regeneration are very remarkable. 

 Kammerer has found that in the common house-fly [Musca 

 domestica) and in the blow-fly {Calliphora vomitoria) 

 amputation of a wing is not followed by any result, yet 

 tearing off a wing from a newly pupated fly is sometimes 



