e brought about quite mechanically, without preconceived plan. This
"mechanical teleology" is a valuable extension of Darwin's monistic
principle of selection to the whole field of cellular physiology and
histology, and is wholly destructive of dualistic vitalism.

The most important advance that evolution has made since Darwin and
the most valuable amplification of his theory of selection is, in my
opinion, the work of Richard Semon: "Die Mneme als erhaltendes Prinzip
im Wechsel des organischen Geschehens" (Leipzig, 1904.). He offers a
psychological explanation of the facts of heredity by reducing them to a
process of (unconscious) memory. The physiologist Ewald Hering had shown
in 1870 that memory must be regarded as a general function of organic
matter, and that we are quite unable to explain the chief vital
phenomena, especially those of reproduction and inheritance, unless
we admit this unconscious memory. In my essay "Die Perigenesis der
Plastidule" (Berlin, 1876.) I elaborated this far-reaching idea, and
applied the physical principle of transmitted motion to the plastidules,
or active molecules of plasm. I concluded that "heredity is the memory
of the plastidules, and variability their power of comprehension." This
"provisional attempt to give a mechanical explanation of the elementary
processes of evolution" I afterwards extended by showing that
sensitiveness is (as Carl Nageli, Ernst Mach, and Albrecht Rau express
it) a general quality of matter. This form of panpsychism finds its
simplest expression in the "trinity of substance."

To the two fundamental attributes that Spinoza ascribed to
substance--Extension (matter as occupying space) and Cogitation
(energy, force)--we now add the third fundamental quality of Psychoma
(sensitiveness, soul). I further elaborated this trinitarian conception
of substance in the nineteenth chapter of my "Die Lebenswunder" (1904)
("Wonders of Life", London, 1904.), and it seems to me well calculated
to afford a monistic solution of many of the antitheses of philosophy.

This important Mneme-theory of Semon and the luminous physiological
experiments and observations associated with it not only throw
considerable light on transformative inheritance, but provide a sound
physiological foundation for the biogenetic law. I had endeavoured
to show in 1874, in the first chapter of my "Anthropogenie" (English
translation; "The Evolution of Man", 2 volumes, London, 1879 and 1905.),
that