DUTCH NIGHTINGALES. 61 



bottom of ponds and lakes. In India frogs are only active 

 during the rains. Frogs are beasts of prey ; they feed 

 upon insects, caterpillars, worms and snails. They catch 

 their victims in much the same way as lizards, by means 

 of their protrusible tongue, which is attached by the front 

 end to the lower jaw. Unlike lizards, frogs will only take 

 their prey on the move ; a frog will not touch a dead fly or 

 other insect. If they can obtain nothing else, frogs devour 

 their neighbours. Besides man, the frog has many ene- 

 mies ; herons, crows, storks, pike and watersnakes are at 

 one with the French in holding that frogs make excellent 

 eating. Of great interest is the development of the frog. 

 To watch the egg being transformed into the adult is to 

 witness the acting of a great historical drama. Events 

 which were spread over hundreds of thousands of years are 

 crowded into a few short weeks. All animals in their devel- 

 opment repeat more or less exactly the history of their race. 

 In the case of the frog development takes place almost 

 wholly outside the egg, so that it can be easily watched. 

 Anyone may see a young frog climb up his own genealo- 

 gical tree. A frog lays about five hundred eggs. These 

 float on the surface of the water in masses which have the 

 appearance of a tapioca pudding. Each egg consists of a 

 dark-brown central part, the yolk, which issunounded by a 

 large amount of gelatinous matter, from which the develop- 

 ing tadpole may possibly derive some nourishment, but of 

 \vhich the chief object is to protect the embryo from changes 

 in temperature. Take some of this spawn and place it in 

 water in a glass pickle-jar and await developments. In 

 India the tadpole soon hatches out, four days being usually 

 sufficient for its incubation ; whereas in cold England the 

 process requires nearly a month. Probably the day after 

 the spawn has been secured, the form of the young tadpole 

 will be discernible in the middle of the albuminous matter. 

 Next they will begin to move about inside the egg, and 

 gradually force their way to the surface, where a terrific 

 struggle for freedom takes place. The middle of the body 



