CHAPTER III 



NEOTENY REGENERATION TEMPERATURE GEOGRAPHICAL 



DISTRIBUTION 



Neoteny. — It has long been known that the larvae of the Spotted 

 Salamander occasionally attain the size of 80 mm. or about o 

 inches, whilst the majority undergo metamorphosis when they 

 are only 40 mm. long. Again, larvae of Triton have been found, 

 in the months of April and May, 80 to 90 mm. long, still with 

 functional gills, but with the sexual organs fully developed. De 

 Eilippi ^ found in one locality in Lombardy, besides a few uoimal 

 fully metamorphosed specimens of only 30 mm. in length, more 

 than forty specimens, which, although they had attained full 

 size, about 55 mm., and were sexually mature, still retained theii' 

 gills. According to him such gill-breathing, otherwise mature 

 specimens, occur constantly in a small lake in the Val Formazzo, 

 on the Italian slope of the Alps, in the province of Ossola. Later 

 Dura^ril " astonished the world by his account of the metamor- 

 phosis of the Mexican gill -breathing Axolotl into an entirely 

 lung-breathing and terrestrial creature, hitherto called Amlily- 

 stoma, and supposed to be not only a different species, but to 

 belong to a different family from the Axolotl, which was known 

 as Sireclon axolotl s. pisciforme, and naturally classed with the 

 Perennibranchiata. 



This discoveiy led to a series of observations and experiments, 

 chiefly conducted by Marie von Chauvin, instigated thereto by 

 Koelliker and by Camerano.^ It was then found that many, 

 if not most of the European Amphibia, both Urodela and Anura, 



' Arch, per zool. e per I'anat. comp., Geneva, 1861, p. 206. 

 - Ann. sci. nat. (5), vii. 1876. 



^ Mem. Ace. Torino, xxxv. 1883, and Atti Ace. Torino, xvii. 1883, p. 84. See 

 also Woltersdorff, Zool. Garten, 1896, p. 327. 



