ms of extinct ancestors' and employ instead:
repetition of forms which accord with the laws of organic development
and lead from the simple to the complex. We must lay special emphasis
on the point that in the embryonic forms even as in the developed
animal forms general laws of the development of the organized
body-substance find expression."

Any one can subscribe to these statements; in truth they contain
something totally different from the "biogenetic principle"; for
Haeckel has really no interest in so general a truth, but is intent
only upon a proof of Descent.

Hertwig continues: "In order to make our train of thought clear, let us
take the egg-cell. Since the development of every organism begins with
it, the primitive condition is in no way recapitulated from the time
when perhaps only single-celled amoebas existed on our planet. For
according to our theory the egg-cell, for instance, of a now extant
mammal is no simple and indifferent, purposeless structure, as it is
often represented, (as according to Haeckel's "biogenetic principle" it
would necessarily be); we see in it, in fact, the extraordinarily
complex end-product of a very long historic process of development,
through which the organic substance has passed since that hypothetical
epoch of single-celled organisms."

"If the eggs of a mammal now differ very essentially from those of a
reptile and of an amphibian because in their organization they
represent the beginnings only of mammals, even as these represent only
the beginnings of reptiles and amphibians, by how much more must they
differ from those hypothetical single-celled amoebas which could as yet
show no other characteristics than to reproduce amoebas of their own
kind."

This is a view which has frequently been clearly expressed by
anti-Darwinians: The egg-cells of the various animals are in themselves
fundamentally different and can therefore have nothing in common but
similarity of structure. In opposition to Hertwig, Haeckel in his
superficial way deduces from it an internal similarity as well. After a
few polite bows before his old teacher, Haeckel, Hertwig thus
summarizes his view: "Ontogenetic (that is, those stages in the
individual development) stages therefore give us only a greatly changed
picture of the phylogenetic (i.e., genealogical) stages as they may
once have existed in primitive ages, but do not correspond to them in
their actual content." This is a very resigned positio