FBOGS AND THEIR RELATIVES 



C, egg con- 



4, eggs before B, eggs after they taining young D, young tadpoles attaching 

 they are laid are laid tadpole themselves to a plant 



t 



E, young tadpole with ex- F, young tadpole with 



ternal gills internal gills (?, young tadpole with hind legs 



H, tadpole with webbed 

 feet 



J, tadpole with legs and arms 

 FIG. 84. Life history of frog. 



J, young frog 



A, one-celled stage B, two-celled stage C, four-celled stage D, eight-celled staga 



E, sixteen-celled 



F, thirty-two 

 celled stage 



G, sixtyfour 

 celled stage 



FIG. 85. Cell division in a frog's egg. 



H, many-celled 

 stage 



