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 experiment when I was a boy—without success—and I have never heard of any one having succeeded with it.[4] 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 condition. It is known as the “axolotl,” and was considered 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 transformation, 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.