THE FROG'S TADPOLE 



291 



frog finds it desirable to plunge into the water. He has 

 now grown a pair of air-holding sacs for breathing (the 

 lungs), opening from the gullet, whilst his gill-slits have 

 entirely closed up and disappeared. He moves quickly, 



FIG. 39. The development of the frog's tadpole into a young frog, 

 i, Very young tadpoles (twice the natural size) adhering by their 

 head suckers (comparable to those of the Ascidian, see Fig. 36) to 

 the leaves of a water plant ; 2 and 2a, the same enlarged to show 

 the external plume-like gills ; 3 and 4, later stages ; 5, the hind legs 

 commencing to appear; 6, with both fore and hind legs; 7, the 

 tail is withering and disappearing; 8, the young frog. 



and with purpose ; he catches small insects, little worms, 

 and such like food, and is a creature of altogether superior 



