e condition involves the process and
development for meeting the other.

And this consideration may be extended very generally to such
organisms as can survive under the same associated natural
conditions, for the history of evolution is so long, and the
power of locomotion so essential to the organism at some period
in its life history, that we cannot philosophically assume a
local history for members of a species even if widely severed
geographically at the present day. At some period in the past
then, it is very possible that the individuals today thriving at
Paris, acquired the experience called out at Upsala. The
perfection of physiological memory inspires no limit to the date
at which this may have occurred--possibly the result of a
succession of severe seasons at Paris; possibly the result of
migrations --and the seed of many flowering plants possess means
of migration only inferior to those possessed by the flying and
swimming animals. But, again, possibly the experi-

112

ence was acquired far back in the evolutionary history of the
flower.[1]

But a further consideration arises. Not only at each moment in
the life of the individual must maximum income and most judicious
expenditure be considered, but in its whole life history, and
even over the history of its race, the efficiency must tend to be
a maximum. This principle is even carried so far that when
necessary it leads to the death of the individual, as in the case
of those organisms which, having accomplished the reproductive
act, almost immediately expire. This view of nature may be
repellent, but it is, nevertheless, evident that we are parts of
a system which ruthlessly sacrifices the individual on general
grounds of economy. Thus, if the curve which defines the mean
rate of reception of energy of all kinds at different periods in
the life of the organism be opposed by a second curve, drawn
below the axis along which time is measured, representing the
mean rate of expenditure of energy on development, reproduction,
etc. (Fig. 7), this latter curve, which is, of course,

[1] The blooms of self-fertilising, and especially of
cleistogamic plants (_e.g._ Viola), are examples of unconscious
memory, or unconscious "association of ideas" leading to the
development of organs now functionless. The _Pontederia crassipes_
of the Amazon, which develops its floating bladders when grown in
water, but aborts them rapidly when grown on land, and seems to
ret