Frogs and their Contributions to Science. 129 



ancient patriarchs. An old farmer told me that he had 

 distinctly recognized, for over twenty years, the peculiar 

 form and tone of one of these burly lords of the pool. 



The tadpole is developed from the egg in from seven to 

 ten days according to the warmth of the air and water. 

 It is instructive to watch from day to day the progress of 

 this embryonic life, and amusing at the last to see some 

 precocious member bursting his cell wall and come wig- 

 gling forth rejoicing as a polliwog. The life of the tadpole 

 is in all respects like the life of a fish. It breathes by gills, 

 and feeds on minute animalcule and vegetable growths. 

 By aid of these, and warmth, and sunlight ; and by the law 

 of his being he approaches in from seven to ten weeks the 

 limit of his aquatic life. Little papillae appear on each 

 side at the back of the neck where legs, the hind legs, of 

 the future frog are soon to burst through. The tail grows 

 shorter and stumpier, and he rises oftenerto the surface to 

 breathe in and out a bubble of air as if to test the veritable 

 lungs that are to replace his primitive gills. At length 

 thejaws, already apparent through the skin, have separated, 

 and the mouth becomes an open fact, and then the upper 

 legs or arms follow in the footsteps of the lower. Little 

 by little the tail has kept decreasing, not dropping off 

 suddenly, but absorbed atom by atom by the action of the 

 capillary blood vessels, until at last it serves no longer as 

 a source of locomotive pride. The change is now com- 

 plete, and the young frog, a tadpole no longer, enters in a 

 new element upon another and higher stage of existence. 

 There is something wonderfully interesting in this change 

 from an inferior to a superior life. Bishop Butler's analo- 

 gical argument to prove the immortality of the soul drawn 

 from the worm, the chrysalis, and the butterfly, might be 

 strengthened here, if need be by another and no less 

 striking illustration. Less grave, also, are the social analo- 

 gies it presents of human polliwogs, whole families of them, 

 [Trans. vi.~] 17 



