142 Darwin as an Anthropologist 
of transformative heredity, and applies the two in conjunction to the 
facts of histology. He lays stress on the significance of functional 
adaptation, which I had described in 1866, under the head of cumu- 
lative adaptation, as the most important factor in evolution. Pointing 
out its influence in the cell-life of the tissues, he puts “cellular 
selection” above “personal selection,” and shows how the finest 
conceivable adaptations in the structure of the tissue may be brought 
about quite mechanically, without preconceived plan. This “me- 
chanical 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 selec- 
tion is, in my opinion, the work of Richard Semon: Die Mneme 
als erhaltendes Prinzip im Wechsel des organischen Gieschehens', 
He offers a psychological explanation of the facts of heredity by 
reducing them to a process of (unconscious) memory. The physio- 
logist 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? I elabo- 
rated 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)°, 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. 
1 Leipzig, 1904. °? Berlin, 1876. 
3 Wonders of Life, London, 1904. 
