96 THE COMMON FROG. [chap. 



After the skeleton, it is the muscular formation of 

 the body which mainly determines its general form 

 and aspect, though occasionally — and often in the 

 Frog's order — the voluntary inflation of the lungs will 

 alone produce a vast modification in an animal's 

 appearance. 



The curious and grotesque resemblance which 

 exists between the figure of the adult frog and that of 

 man has been a common subject of remark. It may 

 then be less surprising to some to learn that there is a 

 great degree of resemblance between the muscles of 

 the Rational and of the Batrachian animals ; though 

 the much greater gulf which separates the Batrachian 

 than the Reptilian class from mammals may lead 

 others to anticipate a greater divergence than in fact 

 exists. 



The frog, however, in its immature stage of exist- 

 ence, is widely different from the adult in its muscular 

 (or myological) furniture, and this for one obvious 

 reason. 



" Muscles " are, as we have shown, par excellence, 

 " organs of motion," and the motions of the tadpole 

 are essentially different from those of the frog. 



The frog, as all know, progresses on land by jumps, 

 and swims through the water by a series of move- 

 ments which are in fact aquatic jumps. This action 

 is familiar to many of us, not only from observation 

 but also by imitation (the frog being a swimming- 

 master given us by nature), but it is none the less a 

 mode of swimming which is very exceptional indeed. 



The tadpole progresses through the water in a very 

 different manner, namely, by lateral undulations of its 



