hologie_ have been improved time after time in the ten editions of my
_Natuerlich Schoepfungsgeschichte_ (1868-1902).[145] A sounded basis for my
phyletic hypotheses, derived from a discriminating combination of the three
great records--morphology, ontogeny, and palaeontology--was provided in the
three volumes of my _Systematische Phylogenie_[146] (1894 Protists and
Plants, 1895 Vertebrates, 1896 Invertebrates).

In my _Anthropogenie_[147] I endeavoured to employ all the known
facts of comparative ontogeny (embryology) for the purpose of
completing my scheme of human phylogeny (evolution). I attempted to
sketch the historical development of each organ of the body, beginning
with the most elementary structures in the germ-layers of the
Gastraea. At the same time I drew up a corrected statement of the most
important steps in the line of our ancestral series.

At the fourth International Congress of Zoology at Cambridge (August
26th, 1898) I delivered an address on "Our present knowledge of the
Descent of Man." It was translated into English, enriched with many
valuable notes and additions, by my friend and pupil in earlier days
Dr. Hans Gadow (Cambridge), and published under the title: _The Last
Link: our present knowledge of the Descent of Man_[148] The
determination of the chief animal forms that occur in the line of our
ancestry is there restricted to thirty types, and these are
distributed in six main groups.

The first half of this "Progonotaxis hominis," which has no support
from fossil evidence, comprises three groups: (i) Protista
(unicellular organisms, 1-5): (ii) Invertebrate Metazoa (Coelenteria
6-8, Vermalia 9-11): (iii) Monorrhine Vertebrates (Acrania 12-13,
Cyclostoma 14-15). The second half, which is based on fossil records,
also comprises three groups: (iv) Palaeozoic cold-blooded Craniota
(Fishes 16-18, Amphibia 19, Reptiles 20): (v) Mesozoic Mammals
(Monotrema 21, Marsupialia 22, Mallotheria 23): (vi) Cenozoic Primates
(Lemuridae 24-25, Tailed Apes 26-27, Anthropomorpha 28-30). An
improved and enlarged edition of this hypothetic "Progonotaxis
hominis" was published in 1908, in my essay _Unsere Ahnenreihe_.[149]

If I have succeeded in furthering, in some degree, by these
anthropological works, the solution of the great problem of Man's
place in nature, and particularly in helping to trace the definite
stages in our ancestral series, I owe the success, not merely to the
vast progress that biology has