2 6o TEXT-BOOK OF ZOOLOGY 



from the hot rays of the sun : for though passing its existence chiefly on 

 land, it cannot live without moisture (see p. 253). At night, however, 

 when the dew refreshes the earth, the frog emerges from its retreat and 

 pursues its chase after all sorts of insects, slugs, and other small 

 creatures. Its hind-legs are a favourite delicacy on the Continent. 



The Toad (Bufo rulgaris). This animal also visits the water only for 

 the purpose of depositing its spawn (which forms necklace-like strings) , 

 and only leaves its retreats at the approach of night or during wet weather. 

 Its dusky, brown or green colour, combined with the numerous wart-like 

 processes which cover the whole of its body, give the animal a strong 

 resemblance to a lump of earth. On the other hand, if the animal 

 hides during the day among large leaves, the skin assumes a greenish 

 colour, whilst if a clay soil is chosen for its habitat the colour changes 

 correspondingly, varying from a brownish-yellow to a light yellow. The 

 skin of the toad secretes a whitish mucus of unpleasant smell and 

 slightly poisonous properties, which, however, can only become 

 dangerous to man if it happens to come in contact with a mucous 

 membrane (eye, mouth). (Protection against enemies; note the 

 behaviour of a dog to whose nose a toad is presented.) The toad's hind- 

 legs are short and weak) whence it is but little capable of leaping. 

 (How does it usually move?) In harmony with its chiefly terrestrial 

 habits, the swimming membranes between the toes of the hind-feet are 

 thick and narrow. As an energetic destroyer of much noxious vermin, 

 especially slugs, the toad renders most useful service to man, and 

 deserves his protection. 



In spring the pools and marshes of Central Europe are resonant with 

 the ghostly bell-like notes of the Bombinator, which seem to proceed 

 from the depth of the water. The colour of the back of this animal, 

 which is not found in England, resembles that of the mud of the bottom 

 (protective colouring). The belly, on the other hand, is very conspicu- 

 ously marked by yellow (B. pachypus) or red (B. iyncus) spots (hence 

 called fire- bellied frogs). When surprised by an enemy and unable to 

 seek refuge in the water, this animal bends back its head, folds its 

 front-legs over its bent back, or turns over on its back and presents its 

 bright-coloured under side to the enemy. It remains in this position 

 until the danger is past, showing that here as in the case of the land 

 salamander we are dealing with a " warning colour," since the bom- 

 binator, like the salamander, secretes a poisoning fluid from its skin. 



The Tree Frog (Hyla arborea) is a favourite though very unreliable 

 weather-prophet. It lives in reed-beds, bushes, trees, etc., where it hunts 

 after all sorts of insects. Its colour frequently bears a striking resem- 

 blance to its surroundings. The usual colour of the animal is a leafy 



