CH. VIII] FROGS, TOADS, AND NEWTS 289 



food but the intestine becomes both shorter and narrower. 

 When these changes are completed the tail is gradually 

 absorbed while the hind legs lengthen so as to compensate 

 for the loss of swimming power by reduction of the tail. 

 The metamorphosis is then complete and the animal 

 comes ashore, a Frog. 



It is possible to defer the metamorphosis by keeping 

 tadpoles in deep water in a vessel with vertical sides and 

 denying all opportunities of resting tne feet upon any 

 object by which the head could be raised above the water. 

 I have known a tadpole attain the age of two years under 

 these conditions and even then possess but very rudi- 

 mentary legs. 



Enemies and Parasites. The enormous number of 

 eggs contained in the spawn deposited by one female 

 makes it clear that the death-rate among frogs is very 

 high. When adult they form food for crows, herons, storks, 

 several species of duck and occasionally some other birds ; 

 rats, moles, shrews, are known to attack them; they 

 are the favourite diet of the grass snake and are eagerly 

 seized by pike and other rapacious fish. No doubt 

 when young they fall victims to all these creatures. As 

 tadpoles they are exposed to other foes ; fish so small 

 as sticklebacks and minnows bite and kill them, but 

 I have never seen them actually swallow any portions; 

 newts, at any rate when pressed by hunger, will eat them, 

 and various aquatic insects such as the larva of the Great 

 Water-beetle, Dyticus marginalis, and the " W T ater-Boat- 

 man," Notonecta glauca, fasten on to them and suck them 

 to death. Judging however by the vast number of young 

 L, 19 



