98 
AMPHIBIANS 
value to man. It destroys many insects. Frogs eat a few 
but hardly enough to entitle them to high rank as beneficial 
animals. Their chief value is as food and as convenient 
forms for dissection in biology courses. 
SUMMARY 
The amphibians are an interesting group which illustrates 
how water animals may have become land animals. The 
frog has well-developed sense organs, legs modified for jump¬ 
ing, and feet for swimming. The skin is moist and helps 
to serve as an organ of respiration. The color markings 
and the habits of the frog serve to protect him from many 
of his enemies. 
QUESTIONS 
What animals belong to this class ? How can you tell them from 
fish? 
Where do the amphibians of your region five ? How many kinds do 
you know? 
See how many kinds of amphibian eggs you can find. 
How long do tadpoles live before they become frogs ? 
What do frogs and toads eat? 
What is fertilization? Metamorphosis? Evolution? Heredity? 
Environment ? 
REFERENCES 
Dickerson, The Frog Book. 
Hodge, Nature Study and Life. 
Holmes, Biology of the Frog. 
Marshall, The Frog. 
Morgan, Embryology of the Frog. 
