If the bloom of these higher alpine flowers is especially pleasing to our own aesthetic 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 aesthetic 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