23 



origin of species and evolution, and the discovery of the 

 smallest change in animal development may indirectly add 

 to the mass of petty details which make up the fund of 

 knowledge needed in discussion of the more weighty phil- 

 osophical questions. In the case of Salamanders this 

 question may become particularly interesting as leading to 

 further knowledge upon the adaptation of animals to en- 

 vironment. All those found here breed in water or in 

 moist places, and at some time or other become strictly 

 terrestrial, only one species (Diemyctylus viridescens) re- 

 turning to a more or less aquatic life. If it can be demon- 

 strated beyond question that this particular species was 

 once strictly a land or water animal, and that, in the 

 struggle for existence, it has been obliged to spend part of 

 its life in a foreign element, and gradually acquired the 

 habit, light would be thrown upon the vexed question of the 

 possibility of such fixation or permanency as is involved in 

 a species. It is already known {vide Darwin's Origin of 

 Species, p. 397, et seq.) that the Black Salamander of the 

 Alps (Salamandra atra) brings forth its young alive and 

 fully formed, the metamorphosis having taken place in dila- 

 tations of the oviducts of the mother. If taken from her, 

 the young are found to have exquisitely feathered gills. 

 Some were removed by Miss Von Chauvin and placed in 

 water, where they swam about like ordinary tadpoles. 

 They underwent the metamorphosis common to other 

 Salamanders, and left the water fourteen weeks later as 

 fully adult as those born from the mother. 



The Urodela. or Salamanders, share with the other am- 

 phibians (Anura and Caecilia*) a more or less complete 

 metamorphosis, with branchial respiration in the young and 

 partial or complete aerial respiration in the adults, and in 

 the elimination of carbon dioxide by the skin. As in birds, 

 reptiles, and fishes, the blood corpuscles are oval and nucle- 



* Professor Cope places the Ccecilians with the Urodela as a family connected 

 through the Amphiumidae. — Bull. No. 34, U. S. Natl. Musetim, p. 34. 



