8 THE FROG chap. 



a frog feed. It lives upon insects, worms, slugs, and the 

 like. Opening its mouth it suddenly darts out a tolerably 

 long, nearly colourless, and very sticky tongue ; if the prey 

 is a small insect, such as a fly, it adheres to the end, and 

 the tongue is quickly drawn back into the mouth, the 

 whole operation being performed with almost inconceivable 

 rapidity. 



Like other animals the frog discharges waste matters 

 from its body. Its droppings or foeces, discharged from the 

 vent, are black and semi-solid. From the same aperture, it 

 expels periodically a quantity of clear fluid, the urine, which 

 is perfectly clear and colourless, and contains little beyond 

 water. 



Sometimes a frog will escape from confinement, leaving 

 its damp box or vivarium for the warm, dry atmosphere of 

 an ordinary room. When this happens the animal is 

 usually found next morning dead and shrunken, and with 

 its naturally moist skin dry and hard. From this it may 

 be inferred that there is a constant evaporation of water 

 from the skin, which, under ordinary circumstances, is 

 checked by a damp atmosphere or by occasional immersion 

 in water. 



Hibernation. — In winter frogs bury themselves in damp 

 places and become sluggish, all manifestations of life becom- 

 ing hardly apparent until the following spring, when they 

 emerge from their holes. In this way they escape the 

 dangers of frost which would otherwise be fatal to them. 

 This suspension of activity during winter is known as 

 hibernation, or the winter sleep. 



Reproduction and Development. — If you examine a 

 number of frogs towards the end of winter — about February 

 in England — you will find that the full-grown females are 

 distinguished from the males, not only by the absence of 



