The Axolotl. 05 
that the larval or gill-bearing stage was the permanent one, espe- 
cially since in it they breed—lay eggs which hatch into similar 
forms, as is the case in permanently gill-bearing species. The 
adult is not so large as the larval form, giving us, as Packard has 
said, an epitome of what has happened in the life of this and other 
classes of animals. For the fossil forms were monsters, yet larval 
and premature as compared with their descendants. Extended 
experiments have been more recently made upon these animals by 
the same lady. She found that younger specimens could be more 
easily forced to transform than older specimens. If the water in 
which they are kept contains but little oxygen, so that they must 
come frequently to the surface for air, they transform more readily 
than if the water is thoroughly aerated. Freulien von Chauvin 
then tried the experiment of converting the axolotl back from the 
higher stage to the lower. In this she succeeded, or at least a 
vigorous larval animal fifteen months old, after being transformed 
to the adult stage (which required twelve days), and being kept out 
of water for another fifteen months, was brought back again to the 
water, to which element it accommodated itself in the course of 
six days. Here it lived three and one-half months. Then it was 
again forced to live on land, which it did six months—till the time 
of its death. 
Some animals were kept in a state of suspended metamorpho- 
sis for three years; that is, when partially transformed, further 
change was prevented by low temperature and being placed at 
night in the water. Then some of these partially transformed 
specimens were forced to return to the larval stage (axolotl), and 
the others to the higher stage (amblystoma). ‘It was believed for 
a long while that the axolotl in its native regions never transformed 
to the amblystoma stage ;_ but it has been proved that, while many 
do not, certainly others do. The latest observations were pub- 
lished in Scéence, July, 1885. Dr. Shufeldt, located in the north- 
west part of New Mexico, has kept the animals in aquaria, study- 
ing their habits and propensities. He has also had opportunity to 
watch them wholly undisturbed in their native ponds. He 
corroborates the several statements made by Freulien von Chauvin. 
He finds also that they are very voracious animals, and that if 
fed abundantly with meat, the amblystoma, or adult animal, is 
much larger. The deeper the water in which they are placed, 
the less likely they are to transform; but in shallow ponds that 
have little or no vegetation, where the bottom is formed of hard 
clay, the larval form is longer retained, and the colour of the 
animal, though usually quite dark, becomes, in this case, very 
light. During the past summer, Dr. Shufeldt saw the ponds 
where were multitudes of these animals rapidly dry up. Those 
caught by the disappearance of the water in their quarter, disap- 
