64 



THE NATURE STUDY COURSE. 



The Transformation. — When the well-developed tadpole 

 rushes to the surface of the water and discharges little air 

 bubbles you will know that its lungs are developing and 

 that it is beginning to use them. A quick inspiration 

 succeeds the little bubble and the tad rapidly descends as if 

 frightened. Its preference for vegetable food is yielding to 

 one for a diet of insects, especially flies ; a concomitant change 



fytcmal sills h_._ 

 disappeared • caduct!. 

 branchiate phase. J; 



fgre limb is developing 



Wind limb is fairly well 

 developed. 



From "Guide to Nature Study. 



is taking place in the length of the intestine — carnivorous 

 animals having as a rule much shorter intestinal canals than 

 vegetable feeders. The young frog, or toad as the case may 

 be, is transforming from a ' four-legged fish ' to a land 

 quadruped — from an herbivorous aquatic to a carnivorous 

 terrestrial creature. Possibly as wonderful changes take 

 place in the life-history of many other animals, but in no 

 other group than this can they be so easily obsetved. There 

 is much for the oldest as well as the youngest to think about. 

 For example, the frog will not need that swimming tail but 

 yet it is not wasted ; it assists in nourishing the animal while 

 it is adapting itself to the change from water-life to land life. 

 How is the substance of the tail carried into the body? 

 Internal changes present many other questions equally 

 difficult 



