2IO 



SCIENCE FROM AN EASY CHAIR 



hanging on to its surface by aid of a tiny sucker, and 

 feeding on the minute green vegetable growths which 





FIG. 43. Stages in the growth from the egg of the common 

 f ro g drawn of the natural size. I. Egg in its jelly-like 

 envelope. 2. Very young tadpoles adhering to weed by 

 their suckers (placed just below the mouth). 3. Very young 

 tadpole, showing two pair of external gills : a third pair is 

 present, but so small as to be invisible without magnifica- 

 tion. 4, 5, 6. Stages in the later growth of the tadpole : 

 the external gills have disappeared, but the legs have not 

 yet made their appearance. 7. Tadpole of full size, with 

 fore and hind legs. 8. The tadpole has now become a 

 small frog, and has left the water. The tail has shrunk, 

 but has not entirely disappeared : it remains throughout life 

 hidden by the skin and the large thighs of the growing frog. 

 This figure has been kindly supplied by Messrs. Macmillan 

 & Co., from Dr. Gadow's volume on the "Amphibia and 

 Reptiles," in the Cambridge Natural History. 



have appeared all over the jelly-like mass. Their rate 

 of growth depends very much on the temperature, and 



