2o6 THE INFANCY OF ANIMALS 



larvae of the spotted salamander, which are normally gill- 

 breathing and living a free life at this stage. But where 

 this experiment is tried it is always found that the uterine 

 gills speedily degenerate and are replaced by a new set 

 adapted for breathing in the water, which the replaced 

 gills, whose function is for the absorption of food, are not. 



