138 



METAMORPHOSIS. 



place. The stages of this metamorphosis are shewn in fig. 82, 5, 

 G, 7, 8. 



The two pairs of limbs appear nearly simultaneously as 

 small buds ; the hinder pair at the junction of the tail and body 

 (fig. 82, 5), and the anterior pair concealed under the opercular 

 membrane. The lungs acquire a greater and greater importance, 

 and both branchial and pulmonary respirations go on together 

 for some time. 



FIG. 82. TADPOLES AND YOUNG OF THE COMMON FROG. (From Mivart. ) 

 i. Recently-hatched Tadpoles twice the natural size. 2. Tadpole with external 



gills. ia. Same enlarged. 3 and 4. Later stages after the enclosure of the gills 



by the opercular membrane. ' 5. Stage with well-developed hind-limbs visible. 



6. Stage after the ecdysis, with both pairs of limbs visible. 7. Stage after partial 



atrophy of the tail. 8. Young Frog. 



When the adult organs are sufficiently developed an ecdysis 

 takes place, in which the gills are completely lost, the provisional 

 horny beak is thrown off, and the mouth loses its suctorial form. 



