THE COMMON FROG. 91 



of a head and tail may be distinguished. 

 Gradually the fin appears around the tail, and 

 the rudiments of the branchice, in the form of 

 tubercles, project from each side of the neck. 

 Within about four days from the deposit of the 

 ova, in a warm climate, such as Italy, the mem- 

 brane is ruptured and the tadpoles become free ; 

 but in our own clime a much longer period is 

 required, and the eggs are not usually hatched 

 for a month after their deposition. 



Soon after the emergence of the tadpoles from 

 the egg the branchice or extended gills attain 

 their full development, when they gradually 

 diminish in size, until at length they become with- 

 drawn into the cavity prepared for their recep- 

 tion, and are closed by a fold of the skin. For 

 some time the tadpoles continue to grow day by 

 day, and increase in bulk without any material 

 change in form. If carefully watched, however, 

 little tubercles or buds will be observed in the 

 course of time to make their appearance both 

 towards the upper and lower portions, or rather 

 forwards and backwards on the body ; these are 

 the rudimentary legs. 



As the latter grow and manifest themselves, 

 the tail, which is in danger of becoming a useless 

 appendage, is gradually absorbed, until the little 

 "froggies," with their stumps of tails, cease to 

 be " tadpoles," and merge into veritable little 



