"This theory [Hering-Butler's] has, indeed, a tentative character,
and lacks symmetrical completeness, but is the more welcome as not
aiming at the impossible. A whole series of phenomena in organic
beings are correlated under the term of MEMORY, CONSCIOUS AND
UNCONSCIOUS, PATENT AND LATENT. . . . Of the order of unconscious
memory, latent till the arrival of the appropriate stimulus, is all
the co-operative growth and work of the organism, including its
development from the reproductive cells. Concerning the modus
operandi we know nothing: the phenomena may be due, as Hering
suggests, to molecular vibrations, which must be at least as distinct
from ordinary physical disturbances as Rontgen's rays are from
ordinary light; or it may be correlated, as we ourselves are inclined
to think, with complex chemical changes in an intricate but orderly
succession. For the present, at least, the problem of heredity can
only be elucidated by the light of mental, and not material
processes."


It will be seen that I express doubts as to the validity of Hering's
invocation of molecular vibrations as the mechanism of memory, and
suggest as an alternative rhythmic chemical changes. This view has
recently been put forth in detail by J. J. Cunningham in his essay on
the "Hormone {0f} Theory of Heredity," in the Archiv fur
Entwicklungsmechanik (1909), but I have failed to note any direct
effect of my essay on the trend of biological thought.

Among post-Darwinian controversies the one that has latterly assumed
the greatest prominence is that of the relative importance of small
variations in the way of more or less "fluctuations," and of