THE AMPHIBIANS 175 
plex internal organs adapt the animal to a free-swimming 
existence for days to come. 
The tadpole is now, to all intents and purposes, a fish— 
a fact most clearly recognized in its form, method of loco- 
Fie. 107.—Metamorphosis of the toad.—Partly after Gags, from Animal Life. 
motion, the arrangement of the gills, and the general plan 
of the circulatory system. 
167. Further growth—In the course of the next few 
weeks hind limbs develop beneath the skin, through which 
they finally protrude. In the same manner, fore limbs arise 
ata later date. In position these organs are like the paired 
fins of fishes, but they are intended for crawling or leaping 
on land, and are modified in accordance with this need. As 
in the higher vertebrates, the limbs develop as arms and 
legs, with long fingers and toes, between which are stretched 
webs of skin, which serve in swimming. 
