158 DEVELOPMENT OF THE TADPOLE. 



and at last fairly breaks its way through the egg and is launched upon a world of 

 dangers, under the various names of tadpole, pollywog, toe-biter or horsenail. 



As it is intended for the present to lead an aquatic life, its breathing apparatus 

 is formed on the same principle as the gills of a fish, but is visible externally, and 

 when fully developed consists of a double tuft of finger-like appendages on each side 

 of the head. The tadpole, with the fully developed branchiae, in shown at fig. a on 

 the accompanying illustration. No sooner, however, have these organs attained their 

 size than they begin again to diminish, the shape of the body and head being at 

 the same time much altered, as is seen in fig. b. In a short time they entirely disap- 

 pear, being drawn into the cavity of the chest and guarded externally by a kind of 

 gill cover. 



Other changes are taking place meanwhile. Just behind the head two little pro- 

 jections appear through the skin, which soon develop into legs, which, however, are not 

 at all employed for progression, as the tadpole wriggles its 

 way through the water with that quick undulation of the flat 

 tail which is so familiar to us all. The creature then bears 

 the appearance represented in fig. c. 



Presently another pair of legs make their appearance in 

 front, the tail is gradually absorbed into the body not falling 

 off, according to the popular belief the branchiae vanish, and 

 the lungs are developed. Fig. d represents a young Frog just 

 before the tail is fully absorbed. 



The internal changes are as marvellous as the external. 

 When first hatched, the young tadpole is to all intents and 

 purposes a fish, has fish-like bones, fish-like gills, and a 

 heart composed of only two chambers, one auricle and one 

 ventricle. But in proportion to its age, these organs receive 

 TADPOLES. corresponding modifications, a third chamber for the heart 



being formed by the expansion of one of the large arteries, 



the vessels of the branchiae becoming gradually suppressed and their place supplied by 

 beautifully cellular lungs, formed by a development of certain membranous sacs that 

 appear to be analogous to the air-bladders of the fishes. 



The Frog, contracted as are its intellectual powers, is yet susceptible to human 

 influence, and can be tamed by kind treatment. Mr. Bell mentions a curious instance 

 where one of these creatures became so completely domesticated, that it used to come 

 nightly from a hole in the skirting-boards where it had established itself, partake of 

 food offered to it by the members of the family, and even jump upon the hearth-rug 

 in winter in order to enjoy the warmth of the fire. A favorite cat, which inhabited 

 the same house, took a strange fancy to the Frog, and these seemingly incongruous 

 companions were to be constantly seen sitting together on the hearth-rug, the Frog 

 nestling under the soft warm fur of the cat. The Frog was, however, more than a 

 year an inmate of the house before it became domesticated, and for many months 

 would retreat to its stronghold when approached. 



Stories of so-called " showers of Frogs " are often seen in the papers, and as a gen- 

 eral rule are little to be credited, the solution of the supposed phenomenon being 

 merely that a shower of rain has induced the creatures to come simultaneously from 

 their retreats. There are, however, instances where credible spectators have seen 

 them fall, and in such cases the little creatures were probably sucked up by a water- 

 spout, or even by a brisk whirlwind, together with the water in which they were dis- 

 porting, carried away for some distance, and at last dropped on the ground, as is 

 sometimes the case with sticks, stones, and leaves, picked up by a passing whirlwind. 



The general color of the common Frog is greenish yellow, or brown, the same 

 individual often passing through all these colors in a few days. A long patch of 

 blackish brown or warm brown is placed behind each of the eyes, and it is yellowish 

 white below. There are no teeth in the lower jaw, and only a single row of very tiny 

 teeth in the upper jaw and on the palate. The ordinary length of the Frog is rather 

 less than three inches, and the total length of the hinder leg is about four inches. 



