616 Studies in the Theory of Descent. 



sionally ascends to a height of 3000 metres 

 (Fatiot)." 



Now it is well known that the atmosphere of 

 the Upper Engadine, 45 like that of other elevated 

 Alpine valleys enclosed by extensive glaciers, is 

 often extraordinarily dry for a long period, a con- 

 dition which appears to me to explain why the 

 black land-salamander is there absent," whilst its 

 near water-living ally occurs in large numbers. 

 The skin of the naked Amphibia generally requires 

 moisture, or else it dries up, and the creature is 

 deprived of a necessary breathing apparatus, and 

 often dies as rapidly as though some important 

 internal organ had been removed. Decapitated 

 frogs hop about for a long time, but a frog which 

 escapes from a conservatory and wanders about 

 for one night in the dry air of a room, is found the 

 following day with dry and dusty skin half dead in 

 some nook, and perhaps perishes in the course of 

 another day if left without moisture. 



All that we know of the biology of the Amphibia 

 is in accordance with this. Thus, all the land- 

 salamanders of southern Italy avoid the hot and 



44 See Fatiot, " Les Reptiles et les Batraciens de la haute 

 Engadine." Geneva, 1873. 



41 I can remember at Upper Engadine a peculiar kind of 

 preserved beef, prepared by simply drying in the air; also the 

 mummification of entire human bodies by drying in the open 

 air, as is practised at Great St. Bernard. 



44 " Faune des Verte'bre's de la Suisse," vol. iii. " Histoire 

 Naturelle des Reptiles et des Batraciens." Geneva, 1873. 



