234 



PROGS, TOADS, AND SALAMANDERS 



Fig. 163. —Eggs of frog. 



indistinct head and a wide tail. This form is known as a 

 "tadpole," or "polUwog." The tadpole lives in the water 

 attached, part of the time at least, to the jellylike mass 



or to water plants, by an 

 adhesive apparatus, or 

 " holder " on the head 

 near the mouth. A little 

 later, the tadpole becomes 

 a free-swimming organism. 

 It breathes by means of 

 small external gills on 

 each side of the head 

 (Fig. 164), and eats mi- 

 nute particles of vegetable 

 matter found in the water. 

 Later, the external gills 

 disappear and are replaced 

 by internal ones. After 

 some time, the hind legs 

 begin to appear and then 

 the front legs, while, at the 



Fig. 164. -Tadpole, highly magnified, ^^^^ time,the tail beCOmeS 



and showing gills (4). shorter and shorter. In 



