with sexual reproduction ; some of these must be more
adapted to the needs of the animals than others. Those
best adapted must be preserved, while the rest are
destroyed. Let us grant the first two conditions to be
true to nature. What chance is there that the requisite
selection will be made ? Those which were most fitted to
breathe the air of the atmosphere would either rise to do
so as frequently, more frequently, or less frequently than
those who were less endowed. If all rose to the surface
to breathe the atmosphere as frequently, all would be
equally exposed to danger, but the fish-eating enemy
would make no choice, he would seize any individual
which happened to come in his way. If the better en
dowed individuals rose more frequently, the danger would
be greater than in the case of the less endowed. If the
better endowed rose less frequently, not needing to come
up to the surface so often, and thus enjoyed greater
security, the others, by using their lungs more frequently,
would soon obliterate the difference brought about by the
slight advantage of birth variation.
For the reasons just assigned, I believe that the change
of the tadpole into the frog was originally brought about,
in the far-off ancestral history of the race, by the trans
forming influence of outward circumstances, and not by
Natural Selection. And this explanation avails to solve
another problem. There are certain animals which were
once regarded as belonging to entirely distinct species,
such, for example, as the axolotl and the amblystoma.
Certainly they differ from one another in a very marked
degree. And yet observation and experiment have proved
that the axolotl under certain conditions can be trans
formed into the amblystoma.
“ In 1867 some axolotls were observed to emerge from the water in
the Jardin des Plantes at Paris, to cast their skins, and to become