theory of
the parallelism between psychical and physical processes. He was
inclined to regard memory in the ordinary sense as a function of the
brain, and memory in general as a function of all organised matter.
Speaking of the psychical life, he says, "Thus the cause which produces
the unity of all single phenomena of consciousness must be looked for in
unconscious life. As we know nothing of this except what we learn from
our investigations of matter, and since in a purely empirical
consideration, matter and the unconscious must be regarded as identical,
the physiologist may justly define memory in a wider sense to be a
faculty of the brain, the results of which to a great extent belong to
both consciousness and unconsciousness."[510] Hering's views were
supported by Haeckel.[511]

In 1893 an American, H. F. Orr,[512] tried to work out a theory of
development and heredity based upon the fundamental idea "that the
property which is the basis of bodily development in organisms is the
same property which we recognise as the basis of psychic activity and
psychic development." He tried also to explain the recapitulation of
phylogeny by ontogeny as due to habit.

The neo-Lamarckian school of American palaeontologists were also in
sympathy with the memory idea, and this was expressed most clearly
perhaps by Cope.[513]

In 1904 appeared the work on this subject which has attracted the most
attention--R. Semon's _Die Mneme_.[514] This was an elaborate treatment of
the question from the materialistic point of view, the main assumption
of Semon's theory being that the action of a stimulus upon the organism
leaves a more or less permanent material trace or "engramm," of such a
nature as to modify the subsequent action of the organism.

Applied to the explanation of heredity and development, Semon's theory
comes to very much the same as Weismann's, with engramms substituted for
determinants, but it has the great advantage of allowing for the
transmission of acquired characters. The application of the concept of
stimulus is valuable and suggestive, but it seems to us that the memory
theory of heredity can be properly utilised only by adopting a frankly
Lamarckian and vitalistic standpoint, and this standpoint Semon
expressly combats. As Ward[515] points out in his illuminating lecture on
heredity and memory--"Records or memoranda alone are not memory, for
they presuppose it. _They_ may consist of physical traces, but memory,
e