make this possibility plausible to us. In the animal
world, and partly also in the plant world, the single individuals of higher
species in their embryonic development pass through states of development,
in the former stages of which not only the individuals of the most
different species look confusingly similar to one another, but also the
embryos in their organization remind us of the perfected state of much
lower classes of beings. In order to give a clear idea of the first
mentioned facts, Haeckel, for instance, in his "Natural History of Creation"
and in his "Anthropogeny," represents by engravings the embryos of
different vertebrates and also of man; representations which--although,
according to the judgment of competent scientists, unfortunately not exact,
but modified, after the manner of stencil plates, in favor of {79} greater
similarity--yet make it quite clear that the similarity of the different
embryos must be very great. We see, for instance, on one table the embryos
of a fish, a salamander, a turtle, a fowl; on a second, those of a pig, an
ox, a rabbit, a man; on a third, those of a turtle, a fowl, a man; and we
find the similarity really great. Examples of the second fact--that
individuals of higher classes or orders in former states of their embryonic
development represent an organization which corresponds to the full-grown
individuals of the lower classes--are: the tail of the human embryo, the
gill-arches of the embryos of reptilia, of birds, of mammalia, and of man.
Now Haeckel here takes up again an idea first suggested by Fritz Mueller, and
derives from these observations the "biogenetic maxim," as he calls it:
"The history of the germ is an epitome of the history of the descent; or,
in other words, ontogeny (the history of the germs or the individuals) is a
recapitulation of phylogeny (the history of the tribe); or, somewhat more
explicitly: that the series of forms through which the individual organism
passes during its progress from the egg-cell to its fully developed state,
is a brief, compressed reproduction of the long series of forms through
which the animal ancestors of that organism (or the ancestral forms of its
species) have passed from the earliest periods of so-called organic
creation down to the present time." In his latest publication, "Ziele und
Wege der heutigen Entwicklungsgeschichte," ("Aims and Methods of the
Present History of Evolution"), he admits into the formulation of his
bi