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HANDBOOK Otf NATURE STUDY 



The head of the young tadpole is not set off from the 

 body, which fact gives the little wiggler the appearance of 

 being simply head and tail. A margin of skin is attached 

 to the upper and to the lower side of the tail and, acting 

 like a tin, enables the animal to swim about freely. On 

 both sides of the head we see little appendages. These are 

 the gills, and with them the animal can breathe the air which 

 is in water. But while the body grows, the gills shrink and 

 soon disappear. Now the animal breathes through lungs, 

 which have grown, while the gills were shrinking. But we 

 noticed some more wonderful changes. A pair of hind legs 



FIG. 5. FROG EGGS AND TADPOLES. 



1, frog eggs ; 2-4, very young tadpoles ; 5-8, older tadpoles. All 

 except 1 reduced. 



began to grow, the tail shrunk, then the front legs appeared 

 as little stumps, and finally when the tail had entirely dis- 

 appeared, the funny little pollywog had changed into a cute 

 little frog. 



The change in its organs enables the animal to lead a dif- 

 ferent life. 



Observations. What differences do you notice between clay and sand? 



