8 THE FROG CHAP. 



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 incon- 

 ceivable rapidity. 



Like other animals the frog discharges waste matters 

 from its body. Its droppings or faces, discharged from 

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

 aperture, it expels periodically a quantity of fluid, 

 the urine, which is perfectly clear and colourless, and 

 contains little besides 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 immer- 

 sion in water. 



Hibernation. In winter frogs bury themselves in damp 

 places, and become sluggish, manifestations of life be- 

 coming 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 you will find that the full-grown females are 

 distinguished from the males, not only by the absence of 

 the pad on the hand, but by the swollen condition of the 

 trunk, due to the interior being distended with eggs. 

 After a time the eggs are laid, being passed out of the 



