If the bloom of these higher alpine flowers is especially
pleasing to our own æsthetic instincts, and markedly conspicuous
to us as observers, why not also especially attractive and
conspicuous to the insect whose mission it is to wander from
flower to flower over the pastures? The answer to this question
involves the hypothesis I would advance as accounting for the
bright colours of high-growing individuals. In short, I believe a
satisfactory explanation is to be found in the conditions of
insect life in the higher alps.
In the higher pastures the summer begins late and
[1] The summer of 1892.
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closes early, and even in the middle of summer the day closes in
with extreme cold, and the cold of night is only dispelled when
the sun is well up. Again, clouds cover the heights when all is
clear below, and cold winds sweep over them when there is warmth
and shelter in the valleys. With these rigorous conditions the
pollinating insects have to contend in their search for food, and
that when the rival attractions of the valleys below are so many.
I believe it is these rigorous conditions which are indirectly
responsible for the bright colours of alpine flowers. For such
conditions will bring about a comparative scarcity of insect
activity on the heights; and a scarcity or uncertainty in the
action of insect agency in effecting fertilization will intensify
the competition to attract attention, and only the brightest
blooms will be fertilized.[1]
This will be a natural selection of the brightest, or the
[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