for he and they are alike identical with the primordial cell； and we
have already noted it as an axiom that things which are identical
with the same are identical with one another。 This is practically
making him one with all living things； whether animal or vegetable；
that ever have existed or ever willsomething of all which may have
been in the mind of Sophocles when he wrote：…
〃Nor seest thou yet the gathering hosts of ill
That shall en…one thee both with thine own self
And with thine offspring。〃
And all this has come of admitting that a man may be the same person
for two days running！ As for sopping common sense it will be enough
to say that these remarks are to be taken in a strictly scientific
sense； and have no appreciable importance as regards life and
conduct。 True they deal with the foundations on which all life and
conduct are based； but like other foundations they are hidden out of
sight； and the sounder they are； the less we trouble ourselves about
them。
What other main common features between heredity and memory may we
note besides the fact that neither can exist without that kind of
physical continuity which we call personal identity？ First； the
development of the embryo proceeds in an established order； so must
all habitual actions based on memory。 Disturb the normal order and
the performance is arrested。 The better we know 〃God save the
Queen；〃 the less easily can we play or sing it backwards。 The
return of memory again depends on the return of ideas associated
with the particular thing that is rememberedwe remember nothing
but for the presence of these； and when enough of these are
presented to us we remember everything。 So； if the development of
an embryo is due to memory； we should suppose the memory of the
impregnate ovum to revert not to yesterday； when it was in the
persons of its parents； but to the last occasion on which it was an
impregnate ovum。 The return of the old environment and the presence
of old associations would at once involve recollection of the course
that should be next taken； and the same should happen throughout the
whole course of development。 The actual course of development
presents precisely the phenomena agreeable with this。 For fuller
treatment of this point I must refer the reader to the chapter on
the abeyance of memory in my book 〃Life and Habit；〃 already referred
to。
Secondly； we remember best our last few performances of any given
kind； so our present performance will probably resemble some one or
other of these； we remember our earlier performances by way of
residuum only； but every now and then we revert to an earlier habit。
This feature of memory is manifested in heredity by the way in which
offspring commonly resembles most its nearer ancestors； but
sometimes reverts to earlier ones。 Brothers and sisters； each as it
were giving their own version of the same story； but in different
words； should generally resemble each other more closely than more
distant relations。 And this is what actually we find。
Thirdly； the introduction of slightly new elements into a method
already established varies it beneficially； the new is soon fused
with the old； and the monotony ceases to be oppressive。 But if the
new be too foreign； we cannot fuse the old and the newnature
seeming to hate equally too wide a deviation from ordinary practice
and none at all。 This fact reappears in heredity as the beneficial
effects of occasional crossing on the one hand； and on the other； in
the generally observed sterility of hybrids。 If heredity be an
affair of memory； how can an embryo； say of a mule； be expected to
build up a mule on the strength of but two mule…memories？ Hybridism
causes a fault in the chain of memory； and it is to this cause that
the usual sterility of hybrids must be referred。
Fourthly； it requires many repeated impressions to fix a method
firmly； but when it has been engrained into us we cease to have much
recollection of the manner in which it came to be so； or indeed of
any individual repetition； but sometimes a single impression； if
prolonged as well as profound； produces a lasting impression and is
liable to return with sudden force； and then to go on returning to
us at intervals。 As a general rule； however； abnormal impressions
cannot long hold their own against the overwhelming preponderance of
normal authority。 This appears in heredity as the normal non…
inheritance of mutilations on the one hand； and on the other as
their occasional inheritance in the case of injuries followed by
disease。
Fifthly； if heredity and memory are essentially the same； we should
expect that no animal would develop new structures of importance
after the age at which its species begins ordinarily to continue its
race； for we cannot suppose offspring to remember anything that
happens to the parent subsequently to the parent's ceasing to
contain the offspring within itself。 From the average age；
therefore； of reproduction； offspring should cease to have any
farther steady； continuous memory to fall back upon； what memory
there is should be full of faults； and as such unreliable。 An
organism ought to develop as long as it is backed by memorythat is
to say； until the average age at which reproduction begins； it
should then continue to go for a time on the impetus already
received； and should eventually decay through failure of any memory
to support it； and tell it what to do。 This corresponds absolutely
with what we observe in organisms generally； and explains； on the
one hand； why the age of puberty marks the beginning of completed
developmenta riddle hitherto not only unexplained but； so far as I
have seen； unasked； it explains； on the other hand； the phenomena of
old agehitherto without even attempt at explanation。
Sixthly； those organisms that are the longest in reaching maturity
should on the average be the longest…lived； for they will have
received the most momentous impulse from the weight of memory behind
them。 This harmonises with the latest opinion as to the facts。 In
his article on Weismann in the Contemporary Review for May 1890； Mr。
Romanes writes： 〃Professor Weismann has shown that there is
throughout the metazoa a general correlation between the natural
lifetime of individuals composing any given species； and the age at
which they reach maturity or first become capable of procreation。〃
This； I believe； has been the conclusion generally arrived at by
biologists for some years past。
Lateness； then； in the average age of reproduction appears to be the
principle underlying longevity。 There does not appear at first
sight to be much connection between such distinct and apparently
disconnected phenomena as 1； the orderly normal progress of
development； 2； atavism and the resumption of feral characteristics；
3； the more ordinary resemblance inter se of nearer relatives； 4；
the benefit of an occasional cross； and the usual sterility of
hybrids； 5； the unconsciousness with which alike bodily development
and ordinary physiological functions proceed； so long as they are
normal； 6； the ordinary non…inheritance； but occasional inheritance
of mutilations； 7； the fact that puberty indicates the approach of
maturity； 8； the phenomena of middle life and old age； 9； the
principle underlying longevity。 These phenomena have no conceivable
bearing on one another until heredity and memory are regarded as
part of the same story。 Identify these two things； and I know no
phenomenon of heredity that does not immediately become infinitely
more intelligible。 Is it conceivable that a theory which harmonises
so many facts hitherto regarded as without either connection or
explanation should not deserve at any rate consideration from those
who profess to take an interest in biology？
It is not as though the theory were unknown； or had been condemned
by our leading men of science。 Professor Ray Lankester introduced
it to English readers in an appreciative notice of Professor
Hering's address； which appeared in Nature； July 18； 1876。 He wrote
to the Athenaeum； March 24； 1884； and claimed credit for having done
so； but I do not believe he has ever said more in public about it
than what I have here referred to。 Mr。 Romanes did indeed try to
crush it in Nature； January 27； 1881； but in 1883； in his 〃Mental
Evolution in Animals；〃 he adopted its main conclusion without
acknowledgment。 The Athenaeum； to my unbounded surprise； called him
to task for this （March 1； 1884）； and since that time he has given
the Heringian theory a sufficiently wide berth。 Mr。 Wallace showed
himself favourably enough disposed towards the view that heredity
and memory are part of the same story when he reviewed my book 〃Life
and Habit〃 in Nature； March 27； 1879； but he has never since
betrayed any sign of being aware that such a theory existed。 Mr。
Herbert Spencer wrote to the Athenaeum （April 5； 1884）； and claimed
the theory for himself； but； in spite of his doing this； he has
never； that I have seen； referred to the matter again。 I have dealt
sufficiently with his claim in my book； 〃Luck or Cunning。〃 ｛43｝
Lastly； Professor Hering himself has never that I know of touche