3 2 Summer Studies of Birds and Books CHAP. 



matus alsus), smallest of all British butterflies. We 

 had found it in the deep valley of Meiringen ; we found 

 it all the way up to the Engstlen Alp, more than four 

 thousand feet higher ; it would collect in clusters on 

 the path, in company with Skippers, and would pack 

 so densely that a foot put down on the little crowd 

 might have killed at least a score. And then again, 

 when we had climbed above the alp to the highest 

 region of all, from seven to eight thousand feet 

 above sea -level, there it was still, flitting about 

 among the patches of melting snow, and doubtless 

 helping to fertilise the exquisite little alpine flowers. 

 Why, one may ask, should these alpine flowers be 

 so intensely bright and fragrant, growing as they do 

 in so cold a climate and in such wild and rugged 

 spots ? Mr. Wallace, in his Tropical Nature, 1 tells 

 us that they need these bright colours in order to 

 attract the butterflies that fertilise them. If it be 

 true that butterflies are really the agents of this 

 reproduction, the theory seems a natural one, and 

 explains the facts. There are few butterflies as high 

 up as eight thousand feet ; we saw, if I recollect 

 right, only two species, the Bedford Blue and a small 

 Fritillary, and these, though common, were not 

 exactly abundant. There is probably, then, great 

 competition for the services of these, and natural 

 selection has been long and hard at work. The 



1 Chapter vi. 



