THE COMMON FROG 85 



both in nutrition and as an aid to respiration. It is an air-breather, 

 but is capable of remaining for a considerable time under water. It 

 retires in winter to the bottom of ponds and marshes, numbers 

 usually congregating and burying themselves in the mud. This 

 hibernation ends in February, and breeding shortly afterwards 

 begins. 



In March the spawn is deposited in masses, to which several 

 individuals contribute, each furnishing many hundred eggs as 

 gelatinous masses with blackish globules scattered through them. 

 These globules soon manifest change, and after a time the young 

 escapes as a tadpole with a short body, circular suctorial mouth and 

 long tail, gills projecting on either side of the head, which answers 

 in position to the gill-opening of fishes. The hind limbs first 

 appear as buds, later the fore-limbs project, the gills disappear 

 as the lungs become more fully developed, and the tail gradually 

 shrinks and disappears, and the animal, which is first fish-like, 

 closely resembling a Urodele Amphibian (or newt) , finally assumes 

 the anourous or adult form. The process is that of metamorphosis, 

 since there is a change not merely of form and proportion, but of 

 internal organs. In its tadpole state the animal was essentially 

 amphibious, but after its change has taken place it is not able to 

 exist under water for any great length of time, but is forced to come 

 to surface to breathe, and be able to live on land. In the successive 

 stages of its development each resembles the adult form of a lower 

 group of animals ; but there has been no passage of one form into 

 another, they have rather descended from common ancestors, and 

 the fish and newt have each reached a stage beyond which the frog 

 has become developed. The frog is most active after rain, when, 

 squatted in the grass, its abdomen rapidily absorbs water. It is 

 found in meadows and other damp places during summer. The 

 food of the frog consists of worms, slugs, woodlice, millipedes, and 

 insects, including their larvae, and it greedily devours wireworms. 

 The prey is captured by means of the tongue, which is covered 

 with a viscid secretion and is attached in front, its free border 

 being behind ; it is rapidly projected from the mouth, the insect 

 adheres to it, and is at once swallowed. 



The COMMON TOAD (Bufo vulgaris) , Fig. 56, belongs to the order 

 Anoura of amphibian Vertebrata and family Bufonidae, which is 

 distinguished by the toes of the hind feet being slightly webbed, 

 but not so perfectly as in the frogs. The toes of the front limbs are 

 not connected by a web. The skin is very prominently provided 

 with warty tubercles and glandular bodies, and paratoid glands 

 (borne on the sides of the head) are developed. A well-developed 

 tongue exists, but no teeth are developed ; the tongue is fixed to the 

 front of the mouth, but is free posteriorly, this latter being protrusible. 



The toad passes through a metamorphosis, appearing first as 

 a tadpole, breathing by outside and then by internal gills, and finally, 



