[1] Grant Allen, I have recently learned, advances in _Science in
Arcady_ the theory that there is a natural selective cause
fostering the bright blooms of alpines. The selective cause is,
however, by him referred to the greater abundance of butterfly
relatively to bee fertilizers. The former, he says, display more
æsthetic instinct than bees. In the valley the bees secure the
fertilization of all. I may observe that upon the Fridolins Alp
all the fertilizers we observed were bees. I have always found
butterflies very scarce at altitudes of 7,000 to 8,000 feet. The
alpine bees are very light in body, like our hive bee, and I do
not think rarefaction of the atmosphere can operate to hinder its
ascent to the heights, as Grant Allen suggests. The observations
on the death-rate of bees and butterflies on the glacier, to be
referred to presently, seem to negative such a hypothesis, and to
show that a large preponderance of bees over butterflies make
their way to the heights.
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brightest will be the fittest, and this condition, along with the
influence of heredity, will encourage a race of vivid flowers. On
the other hand, the more scant and uncertain root supply, and the
severe atmospheric conditions, will not encourage the grosser
struggle for existence which in the valleys is carried on so
eagerly between leaves and branches--the normal offensive and
defensive weapons of the plant--and so the struggle becomes
refined into the more æsthetic one of colour and brightness
between flower and flower. Hence the scant foliage and vivid
bloom would be at once the result of a necessary economy, and a
resort to the best method of securing reproduction under the
circumstances of insect fertilizing agency. Or, in other words,
while the luxuriant growth is forbidden by the conditions, and
thus methods of offence and defence, based upon vigorous
development, reduced in importance, it would appear that the
struggle is mainly referred to rivalry for insect preference. It
is probable that this is the more economical manner of carrying
on the contest.
In the valleys we see on every side the struggle between the
vegetative organs of the plant; the soundless battle among the
leaves and branches. The blossom here is carried aloft on a
slender stem, or else, taking but a secondary part in the
contest, it is relegated to obscurity (P1. XII.). Further up on
the mountains, where the conditions are more severe and the
supplies less abundant, the leaf and branch assume lesser
dimensions, for they are costly weapons to provide and the
elements are unfriendly
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to their existence (Pl. XIII.). Still higher, approaching the
climatic limit of vegetable life, the struggle for existence is
mainly carried on by the æsthetic rivalry of lowly but
conspicuous blossoms.
As regards the conditions of insect life in the higher alps, it
came to my notice in a very striking manner that vast numbers of
such bees and butterflies as venture up perish in the cold of
night time. It appears as if at the approach of dusk these are
attracted by the gleam of the snow, and quitting the pastures,
lose themselves upon the glaciers and firns, there to die in
hundreds. Thus in an ascent of the Tödi from the Fridolinshüte we
counted in the early dawn sixty-seven frozen bees, twenty-nine
dead butterflies, and some half-dozen moths on the Biferten
Glacier and Firn. These numbers, it is to be remembered, only
included those lying to either side of our way over the snow, so
that the number must have mounted up to thousands when integrated
over the entire glacier and firn. Approaching the summit none
were found. The bees resembled our hive bee in appearance, the
butterflies resembled the small white variety common in our
gardens, which has yellow and black upon its wings. One large
moth, striped across the abdomen, and measuring nearly two inches
in length of body, was found. Upon our return, long after the
sun's rays had grown strong, we observed some of the butterflies
showed signs of reanimation. We descended so quickly to avoid the
inconvenience of the soft snow that we had time for no
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close observation on the frozen bees. But dead bees are common
objects upon the snows of the alps.
These remarks I noted down roughly while at Linthal last summer,
but quite recently I read in Natural Science[1] the following
note:
"Late Flowering Plants.--While we write, the ivy is in flower, and
bees, wasps, and flies are jostling each other and struggling to
find standing-room on the sweet-smelling plant. How great must be
the advantage obtained by this plant through its exceptional
habit of flowering in the late autumn, and ripening its fruit in
the spring. To anyone who has watched the struggle to approach
the ivy-blossom at a time when nearly all other plants are bare,
it is evident that, as far as transport of pollen and
cross-fertilization go, the plant could not flower at a more
suitable time. The season is so late that most other plants are
out of flower, but yet it is not too late for many insects to be
brought out by each sunny day, and each insect, judging by its
behaviour, must be exceptionally hungry.
"Not only has the ivy the world to itself during its flowering
season, but it delays to ripen its seed till the spring, a time
when most other plants have shed their seed, and most edible
fruits have been picked by the birds. Thus birds wanting fruit in
the spring can obtain little but ivy, and how they appreciate the
ivy berry is evident
[1] For December, 1892, vol. i., p. 730.
107
by the purple stains everywhere visible within a short distance
of the bush."
These remarks suggest that the ivy adopts the converse attitude
towards its visitors to that forced upon the alpine flower. The
ivy bloom is small and inconspicuous, but then it has the season
to itself, and its inconspicuousness is no disadvantage, _i.e._
if one plant was more conspicuous than its neighbours, it would
not have any decided advantage where the pollinating insect is
abundant and otherwise unprovided for. Its dark-green berries in
spring, which I would describe as very inconspicuous, have a
similar advantage in relation to the necessities of bird life.
The experiments of M. C. Flahault must be noticed. This
naturalist grew seeds of coloured flowers which had ripened in
Paris, part in Upsala, and part in Paris; and seed which had
ripened in Upsala, part at Paris, and part at Upsala. The flowers
opening in the more northern city were in most cases the
brighter.[1] If this observation may be considered indisputable,
as appears to be the case, the question arises, Are we to regard
this as a direct effect of the more rigorous climate upon the
development of colouring matter on the blooms opening at Upsala?
If we suppose an affirmative answer, the theory of direct effect
by sun brightness must I think be abandoned. But I venture to
think that the explanation of the Upsala
[1] Quoted by De Varigny, _Experimental Evolution_, p. 56.
108
experiment is not to be found in direct climatic influence upon
the colour, but in causes which lie deeper, and involve some
factors deducible from biological theory.
The organism, as a result of the great facts of heredity and of
the survival of the fittest, is necessarily a system which
gathers experience with successive generations; and the principal
lesson ever being impressed upon it by external events is
economy. Its success depends upon the use it makes of its
opportunities for the reception of energy and the economy
attained in disposing of what is gained.
With regard to using the passing opportunity the entire seasonal
development of life is a manifestation of this attitude, and the
fleetness, agility, etc., of higher organisms are developments in
this direction. The higher vegetable organism is not locomotory,
save in the transferences of pollen and seed, for its food comes
to it, and the necessary relative motion between food and
organism is preserved in the quick motion of radiated energy from
the sun and the slower motion of the winds on the surface of the
earth. But, even so, the vegetable organism must stand ever ready
and waiting for its supplies. Its molecular parts must be ready
to seize the prey offered to it, somewhat as the waiting spider
the fly. Hence, the plant stands ready; and every cloud with
moving shadow crossing the fields handicaps the shaded to the
benefit of the unshaded plant in the adjoining field. The open
bloom
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is a manifestation of the generally expectant attitude of the
plant, but in relation to reproduction.
As regards economy, any principle of maximum economy, where many
functions have to be fulfilled, will, we may very safely predict,
involve as far as possible mutual helpfulness in the processes
going on. Thus the process of the development towards meeting any
particular external conditions, A, suppose, will, if possible,
tend to forward the development towards meeting conditions B; so
that, in short, where circumstances of morphology and physiology
are favourable, the ideally economical system will be attained
when in place of two separate processes, a, ß, the one process y,
cheaper than a + ß, suffices to advance development
simultaneously in both the directions A and B. The economy is as
obvious as that involved in "killing two birds with the one
stone"--if so crude a simile is permissible--and it is to be
expected that to foster such economy will be the tendency of
evolution in all organic systems subjected to restraints as those
we are acquainted with invariably are.
Such economy might be simply illustrated by considering the case
of a reservoir of water elevated above two hydraulic motors, so
that the elevated mass of water possessed gravitational
potential. The available energy here represents the stored-up
energy in the organism. How best may the water be conveyed to the
two motors [the organic systems reacting towards conditions A and
B] so
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that as little energy as possible is lost in transit? If the
motors are near together it is most economical to use the one
conduit, which will distribute the requisite supply of water to
both. If the motors are located far asunder it will be most
economical to lay separate conduits. There is greatest economy in
meeting a plurality of functions by the same train of
physiological processes where this is consistent with meeting
other demands necessitated by external or internal conditions.
But an important and obvious consequence arises in the supply of
the two motors from the one conduit. We cannot work one motor
without working the other. If we open a valve in the conduit both
motors start into motion and begin consuming the energy stored in
the tank. And although they may both under one set of conditions
be doing useful and necessary work, in some other set of
conditions it may be needless for both to be driven.
This last fact is an illustration of a consideration which must
enter into the phenomenon which an eminent biologist speaks of as
physiological or unconscious "memory,"[1] For the development of
the organism from the ovum is but the starting of a train of
interdependent events of a complexity depending upon the
experience of the past.
[1] Ewald Hering, quoted by Ray Lankaster, _The Advancement of
Science_, p. 283.
111
In short, we may suppose the entire development of the plant,
towards meeting certain groups of external conditions,
physiologically knit together according as Nature tends to
associate certain groups of conditions. Thus, in the case in
point, climatic rigour and scarcity of pollinating agency will
ever be associated; and in the long experience of the past the
most economical physiological attitude towards both is, we may
suppose, adopted; so that the presence of one condition excites
the apparent unconscious memory of the other. In reality the
process of meeting the one 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
retain this power of adaptation to the environment for an
indefinite period of time, must act in each case upon an
unconscious memory based upon past experience. Many other cases
might be cited.
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physiologically dependent on the former, must be of such a nature
from its origin to its completion in death, that the condition is
realized of the most economical rate of expenditure at each
period of life.[1] The rate of expenditure of energy at any
period of life is, of course, in such a curve defined by the
slope of the curve towards the axis of time at the period in
question; but this particular slope _must be led to by a previous
part of the curve, and involves its past and future course to a
very great extent_.
{Fig. 7}
There will, therefore, be impressed upon the
organism by the factors of evolution a unified course of
economical expenditure completed only by its death, and which
will give to the developmental progress of the individual its
prophetic character.
In this way we look to the unified career of each organic unit,
from its commencement in the ovum to the day
[1] See _The Abundance of Life_.
114
when it is done with vitality, for that preparation for momentous
organic events which is in progress throughout the entire course
of development; and to the economy involved in the welding of
physiological processes for the phenomenon of physiological
memory, wherein we see reflected, as it were, in the development
of the organism, the association of inorganic restraints
occurring in nature which at some previous period impressed
itself upon the plastic organism. We may picture the seedling at
Upsala, swayed by organic memory and the inherited tendency to an
economical preparation for future events, gradually developing
towards the æsthetic climax of its career. In some such manner
only does it appear possible to account for the prophetic
development of organisms, not alone to be observed in the alpine
flowers, but throughout nature.
And thus, finally, to the effects of natural selection and to
actions defined by general principles involved in biology, I
would refer for explanation of the manner in which flowers on the
Alps develop their peculiar beauty.
115