274 



ELEMENTS OF GENERAL SCIENCE 



cells. This mass of cells elongates; mouth, eyes, and tail 

 appear; and the young animal wriggles out of the inclosing 

 jelly. Soon it has the complete form of the familiar tadpole. 



FIG. 127. Development of the frog 



A, eggs ; B and C, early stages of the embryo ; D, tadpole as commonly seen ; 



E and F, legs appearing ; G and H, front legs appearing and tail disappearing ; 



/, mature frog. B and C are enlarged much more than the other parts of the 



illustration, the others being approximately natural size 



301. The tadpole. The tadpoles, or polliwogs, which are 

 commonly seen in the ponds and ditches are the young of 

 frogs, toads, or related animals. The very numerous small, 



