TADPOLES AND FROGS 215 



" Growth from the egg " is a long story ; we must revert 

 now to the tadpoles and their parents. 



There is a tradition that Dr. Edwards, the father of 

 Henri and grandfather of Alphonse Milne Edwards, 

 directors of the Natural History Museum of Paris, kept 

 some tadpoles in a sort of cage sunk in the Seine, so that 

 they could not come to the surface to breathe air nor 

 escape on to the land, and that they grew to be very big 

 tadpoles, much larger than the size at which tadpoles 

 usually change into frogs. I tried to repeat this experi- 

 ment when I was a boy without success and I have 

 never heard of any one having succeeded with it. 1 It is 

 not cited or credited at the present day. But some thirty 

 years ago it was discovered that something of this kind 

 happens in the case of the Mexican salamander. The 

 English " newts " and the so-called salamanders are 

 creatures of lizard-like shape, which are closely related to 

 frogs and toads. They lay eggs in the water, and the 

 young are tadpoles, with beautiful large plume-like gills 

 on each side of the head. The tadpole of the common 

 English newt may either lose its gills and leave the water 

 in the summer, if it was hatched early in the season, or 

 may remain longer in the gilled condition, and grow to 

 more than two inches in length, if it was hatched late. 

 In certain lakes in Mexico there is a tadpole-like creature 

 with gill-plumes, which grows to eight inches or more in 

 length, and becomes adult and breeds when in that con- 

 dition. It is known as the " axolotl," and was considered 



1 I am told by Mr. Boulenger, of the Natural History Museum, who 

 is the greatest authority on these animals, that the explanation of this 

 is that unawares Dr. Edwards made use of the young tadpoles of the 

 obstetric toad (Alytes], which is very common near Paris, though it 

 does not occur in England. These tadpoles regularly grow to be three 

 inches and more in length (see Fig. 44 B). Dr. Edwards thought 

 he had used the tadpoles of the common frog, but had, by accident, 

 got hold of those of Alytes. 



