216 SCIENCE FROM AN EASY CHAIR 



to be a distinct kind of gill-bearing adult tadpole-like 

 animal similar to some few others which are known 

 (Siren and Necturus). When, however, they were brought 

 to Europe and kept in a cage with only a small provision 

 of water, some of these axolotls were found to leave the 

 water, lose their gills, change their colour and shape in 

 several respects, and become, in fact, transformed into a 

 terrestrial salamander, of a kind already known in North 

 America. It was thus established that the axolotl of the 

 Mexican lake is nothing more nor less than the tadpole 

 of a species of salamander or newt, which has " given up " 

 the habit of leaving the water, and actually grows to full 

 size, and lays its eggs without becoming converted into a 

 gill-less land-dwelling creature ! The greatest interest was 

 excited forty years ago, when the discovery was made 

 that, by gradually drying up the water in which the 

 axolotl is kept, it can be induced to resume its transforma- 

 tion, and become changed into a salamander. Thus, the 

 notion of converting the tadpoles of the common frog into 

 very big tadpoles by preventing them from leaving the 

 water, seems not to have been an unreasonable one. 



There are some very big kinds of tadpoles, which are 

 the young of toads of other kinds than our British species. 

 In England we have only two kinds of frogs the common 

 frog and the edible frog and two kinds of toads, the 

 common toad and the natter-jack or crawling toad (dis- 

 tinguished by the pale line along the middle of his back). 

 But on the Continent of Europe there are others besides 

 those which we have. There is the beautiful little green 

 tree-frog, and there are the fire-bellied toad, and the 

 obstetric toad (the male of which carries the eggs after 

 they are laid, coiled in a string around his hind legs) ; 

 and then there is the little spur-heeled toad (Pelobates 

 fuscus), which smells like garlic, and is remarkable for 

 having a broad, horny claw on his heel. This toad is 



