462 THE WONDER OF LIFE 



lost all trace of its tail, hops ashore a little frog about 

 three months old. 



It is very interesting to observe that in this single life- 

 history there is first of all nutritive dependence on the 

 legacy of yolk, then a period of vegetarian diet, then a 

 somewhat omnivorous period, then a fast, then a carnivor- 

 ous time, and finally an insectivorous adult lif e. Similarly, 

 as regards respiration, there is great variety. The newly- 



FIG. 76. Male Edible Frog, Rana esculenta, showing the resonating 

 , sacs protruded from the corners of the mouth. From a specimen. 



hatched larva breathes through its skin ; it has a first set 

 of gills ; it develops gill-clefts ; a second set of gills arising 

 under the gill-covering replaces the first set ; when it is 

 two months old it breathes by both gills and lungs ; the 

 gills disappear and the frogling is a lung-breather ; but 

 all through the winter the frog harks back to the 

 primitive cutaneous respiration. 



As regards recapitulation, it goes without saying that 



