146 Scientific Proceedings, Royal Dublin Society. 
nation I am unable to refer to its author. The following pages 
contain a suggestion on the matter, which occurred to me while 
in the Linthal district of Switzerland last summer. I have some 
compunction in offering the suggestion of an unprofessional. 
If the bloom of these higher alpine flowers is especially 
pleasing to my own esthetic instincts, and markedly conspicuous 
to me as an observer, why not also especially attractive and con- 
spicuous 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 satis- 
factory explanation is to be found in the conditions of insect life 
in the higher alps.’ 
In the higher pastures the summer begins late and 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. These rigorous conditions the fertilizers have to con- 
tend with in their search for food, and that when the rival attrac- 
tions 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.’ 
This will be a natural selection of the brightest, or the 
1 Mr. 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 esthetic instinct than 
bees. In the valley the bees secure the fertilization of all. I may observe that upon 
the Fridolins Alp all the fertilizers I observed were bees. I have always found 
butterflies very scarce at altitudes of 7000 to 8000 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 Mr. 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 hypotheses, and to show that a large preponderance 
of bees over butterflies make their way to the heights. 
