Since the time when Duméril made known the transformation of a number
of Axolotls into the so-called Amblystoma form, this Mexican Amphibian
has been bred in many European aquaria, chiefly with the view to
establish the conditions under which this transformation occurred, so
as to be enabled to draw further conclusions as to the true causes of
this exceptional and enigmatical metamorphosis.
Although the Amphibians propagated freely, the cases in which
transformation occurred remained extremely rare, and it was not once
possible to reply to the main question, viz. whether this metamorphosis
was determined by external conditions or by purely internal causes;
to say nothing of the possibility of there perhaps being discoverable
certain definite external influences by means of which the
metamorphosis could have been induced with certainty. But while these
points are undecided all attempted theoretical interpretations of the
phenomenon must be devoid of a solid basis.
It appeared to me from the first that the history of this
transformation of the Axolotl was of special theoretical value; indeed
I believed that it might possibly furnish a special case for deciding
the truth of those ground-principles, according to which the origin of
this species is represented by the two conflicting schools as a case of
transformation or as one of heterogenesis. I therefore determined to
make some experiments with the Axolotl myself, in the hopes of being
fortunate enough to be able to throw some light upon the subject.
In the year 1872 Prof. v. Kölliker was so good as to leave with me
five specimens of his Axolotls, bred in Würzburg, and these furnished
a numerous progeny in the following year. With these I carried out the
idea, the theoretical bearing of which will be shown subsequently,
whether it would not be possible to force all the larvæ, or at any
rate, the greater majority, to undergo transformation by exposing them
to conditions of life which made the use of gills difficult, and that
of lungs more easy; in other words, by compelling them to live partly
on land at a certain stage of life.
During that year indeed I obtained no results, most of the larvæ
perishing before the time for such an experiment had arrived, and the
few survivors did not undergo transformation, but lived on to the
following spring and then also died one after the other. Through long
absence from Freiburg, necessitated by other labours, I had evidently
left them without sufficient care and attention. I was thus led to
the conviction, which was more fully confirmed subsequently, that no
results can be obtained without the greatest care and attention in
rearing, towards which single object all one’s interest should be
concentrated, and it must not be considered irksome to have to devote
daily for many months a large amount of time to this experiment. As it
was evident that I could not afford this time without calling in other
aid, I hailed with pleasure an opportunity of witnessing the experiment
performed by other hands.
A lady living here (Freiburg), Fräulein v. Chauvin, undertook to rear
a number of my larvæ of the following year which had just hatched,
and in accordance with my idea to make the experiment of forcibly
compelling them to adopt the Amblystoma form. How completely this was
accomplished will be seen from the following notes by the lady herself,
and it will no less appear that these results were only obtained by
that care in treatment and delicacy of observation which she devoted to
the experiments.