35386 THE VIVARIUM. 
therefore classed among the Perennibranchiata, or perpetual 
bearers of external gills. However, in 1865, this classification 
was proved to be a wrong one; for in January of that year some 
Axolotls which had been for several months in the Reptilium of 
the Musée d’Histoire Naturelle, at Paris, began to breed. The 
eggs which were deposited hatched in about four weeks, and the 
growth of the larvee was carefully watched by Professor A. 
Duméril. In the early part of September, when the young 
Axolotls had grown almost as large as their parents, it was 
noticed that one of them had commenced to pass through a 
metamorphosis similar to that which is experienced by a young 
Newt before it arrives at maturity. In a few weeks the branchize 
were gradually absorbed, the gill openings closed up, the large 
dorsal and caudal fin disappeared, the tail assumed the appear- 
FIG, 98.—AN AMBLYSTOME (Amblystoma tigrinwm). 
ance of that of an ordinary Salamander, the toes became narrowed 
and lost their appendages, yellow spots appeared upon the skin, 
changes took place in regard to the skull and dentition, and the 
animal commenced to breathe altogether by means of its lungs, 
and ultimately left the water. 
In the early part of the October following others of the young 
Axolotls underwent a like metamorphosis, until finally, out of 
several hundreds of Tadpoles, about thirty became apparently 
perfect Amblystomes. The parents, however, passed through no 
such change at all. 
The account which Professor Duméril published of these un- 
expected metamorphoses excited a great deal of interest among 
naturalists, and many of them procured Axolotls for the purpose 
of observation and experiment. 
