influences (which may vary according to
the climate, etc.: Geoffroy St. Hilaire), Eimer mentions as important
and active factors in this development, (1). The use and disuse of
organs (Lamarck); (2). The struggle for existence (Darwin); (3). The
correlation of organs, that is, the inner relation of organs in
consequence of which a change in one organ may occasion a sudden change
in another organ; (4). Cross fertilization and hybridism.

It is clear that with reference to the factors of evolution Eimer is,
and perhaps not unreasonably, an eclectic, whose aim is to do justice
to the predecessors of Darwin as well as to Darwin himself. His
antagonism to Darwin and Weismann in this work is still quite moderate,
although even here it appears with sufficient clearness that selection
and the struggle for existence, the two principles peculiarly
characteristic of Darwinism, do not give rise to new species, but can
at best only separate and differentiate species already existing.

The second part of Eimer's work dealing with the origin of species,
which appeared after an interval of ten years, bears the title:
"Orthogenesis of Butterflies." The Origin of Species, II. Part (2
tables and 235 illustrations in the text). Leipzig, 1897. In this book
substantially the same thoughts occupy the mind of the author as in the
former volume, but in many respects they are more mature, and
conspicuously more definite and precise. The most salient features are
the following:

1. Eimer establishes his theory by means of very minute observations on
a definite species of animals, viz., butterflies.

2. He attributes evolution almost exclusively to development along
definitely determined lines.

3. He proves the utter untenableness of Darwinian principles and
repudiates them unqualifiedly.

4. In a very distinct and severe manner he gives expression to his
opposition to his former friend Weismann.

5. He attacks with telling effect the fantastic Darwinian "Mimicry."

In his "General Introduction" Eimer first treats of Orthogenesis in
opposition to the Darwinian theory of selection. The very first
sentence gives evidence of this antagonism: "According to my
investigation, organic growth (Organophysis), which is rendered
dependent on the plasm by permanent external influences, climate and
nourishment, and the expression of which is found in development along
definitely determined lines, (Orthogenesis), is the principal cause of
transforma