CHAPTER VI. 



THE AMPHIBIANS. 



• 



Amphi, double ; Bios, life ; a double life. That is the meaning 

 of amphibious, a term formerly applied to those animals, reptiles, 

 and even some birds that are as much at home in water as on 

 land, resorting to each in turn at their pleasure ; as, for example, 

 crocodiles, otters, seals, turtles, etc., in addition to frogs and 

 newts. The true amphibians are, however, only those creatures 

 whose organism fits them to live and to breathe both, in water 

 and on land ; not like the above animals, breathing atmospheric 

 air only ; but like fish at first, breathing by means of gills, in- 

 dependent of the upper air ; and then, in their mature state, 

 by means of lungs. They also possess the remarkable faculty 

 of" cutaneous respiration, that is, a power in the skin to effect 

 changes in the blood usually performed by the lungs, which in 

 these creatures are inefficient. Like fishes, they are born or 

 hatched from an egg deposited in the water. Like fishes, their 

 locomotion at first is by swimming, by means of .their long 

 fin-like tail ; their circulation and other functions are like those 

 of fishes ; but withal, they undergo a metamorphosis. Their 

 gills are gradually absorbed and lungs are developed : in frogs and 

 toads the* tail is absorbed and limbs are developed; and other 

 organs are gradually growing or being perfected, until they are 

 ready to begin their new life on land. Their metamorphosis is 

 not like that of insects which undergo a period of torpidity in 

 the chrysalis state, and then emerge into the perfect imago ; but 

 it is a transformation which may be actually watched, as the growth 

 of eyes, mouth, and other organs are produced or developed from 

 the yolk of the egg. 



The Amphibians, though represented in Britain by frogs, toads, 

 and newts only, include a large group presenting great diversity 

 of form in other parts of the world. They are caudata, with a 

 tail, ecaudata, without a tail ; apoda, without feet ; frogs and 

 newts with four perfect limbs, vermiform, or ophipmorpha, with 

 a worm-like, or snake ; like exterior, together with some extinct 



