COMMON FROG. 559 



These tadpoles are so perfectly unlike the animals in their complete 

 state, person not conversant in natural history would hardly 



suppose them to bear any relationship to the frog j since, on a gene- 

 ral view, they appear to consist merely of head and tail. Their 

 motions are extremely lively, and they are often seen in such vast 

 numbers as to blacken the whole water with their legions. They 

 live on the leaves of duckweed and other small water-plants, as well 

 as on various kinds of animalcules, &c. and when arrived at a larger , 

 size, they may even be heard to gnaw the edges of the leaves on 

 which tiiey feed, their mouths being furnished with extremely mi- 

 nute teeth or denticulations. The tadpole "is also furnished with a 

 small kind of tubular sphincter or sucker, beneath the lower jaw, 

 by the help of which it hangs at pleasure to the under surface of 

 the aquatic plants, &c. From this part it also occasionally hangs, 

 when very young, by a thread of gluten, which it seems to manage 

 in the same manner as some of the smaller slugs have been observed 

 to practise. Its interior organs differ, if closely inspected, from 

 those of the future frog, in many respects ; the intestines in parti- 

 cular are always coiled into a flat spiral, in the manner of a cable in- 

 miniature. 



When the tadpoles have arrived at the age of about five or six 

 weeks, the hind legs make their appearance, gradually increasing 

 in length and size; and, in about a fortnight afterwards, or some- 

 times later, are succeeded by the fore legs, which are indeed 

 formed beneath the skin much sooner, and are occasionally pro- 

 truded, and again retracted by the animal, through a small foramen 

 on each side of the breast, and are not completely stretched forth 

 till the time just mentioned. The animal now bears a kind of am- 

 biguous appearance, partaking of the form of a frog and a lizard. 

 The tail at this period begins to decrease, at first very gradually 

 and at length so rapidly as to become quite obliterated in the space 

 of a day or two afterwards. The animal now ventures upon land, 

 and is seen wandering about the brinks of its parent waters, and 

 sometimes in such multitudes as to cover a space of many yards in 

 extent. This is the phenomenon which has so frequently embar- 

 rassed the minds not only of the vulgar, but even of some superior 

 characters in the philosophic world ; who, unable to account for 

 the legions of these animals with which the ground is occasionally 

 covered in certain spots, at the close of summer, have been led into 



