•hap. VI] 



ANIMALS 



12: 



The high regions of the Alps are indeed poorer in insects than the 

 lUTOunding lowlands ; yet, as Hermann Miillcr has shown, flowers are 

 ot less frcciucnth' visited by insects there than in the plains. More 

 nportant than the reduced total number of insects is the quite altered 

 umcrical relation among the different groups. Thus, according to 

 lermanii Miillcr, Apidae, except humble-bees, fall off rapidly in numbers 

 3 the altitude increases. Lepidoptera, on the contrary, show a consider- 

 ble increase. Accordingl)' bee-flowers decrease and lepidopteron-flowers 

 icrease. The latter, according to Loew, number in the Alps ^"i, species, 

 ut only 36 in the VVestphalian lowlands. 



Many genera are represented in the plains by bee-flowers, in the Alps 

 y lepidopteron-flowers ; for example, Gentiana. Rhinanthus, Viola. One 

 lid the same species may even 

 xhibit corresponding variations. The 

 owers of Viola tricolor (Fig. 65, 2) 

 •e short-spurred in the plains, corre- 

 wnding to the short proboscis of 

 le bees, their pollinators ; the variety 

 pestris is long-spurred, corresponding 

 I the long proboscis of Lepidoptera. 

 he purely alpine Viola calcarata 

 as long-spurred lepidopteron-flowers 

 ""ig. 6,5, 1). Primula farinosa, accord- 

 g to Hermann Mi.iller, has in the 

 ains, where its pollinators are bees, 



considerably wider entrance to its 

 3wer than it has on alpine heights, 

 here it is practicall}' visited by 

 epidoptera onh'. 



The Pyrenees are poorer in Lepi- 

 )ptera than are the Alps, but on the other hand are richer in insects 



at have not produced through natural selection definite forms of flowers ; 

 pidopteron-flowers are accordingly feebly represented (MacLeod). 



The Norwegian plateau is poor in insects owing to the shortness and 

 etness of the summer ; adaptations for cross-pollination have therefore 

 idergone a considerable reduction. 



Of the 76 alpine and arctic species of the Dovrefjeld, according to a compila- 

 >n by Loew, there are 2 anemophilous species (Oxyria digj-na and Thalictrum 

 Jinum), whilst the 74 entomophilous species exhibit the following arrangements: 

 If-pollination is invariably or usuallj- prevented in 12 species = 16-2 % ; self- 

 'llination as well as cross-pollination occurs in 40 species = 54 % ; self-pollination 

 regular or easily accomplished in 22 species = 297 %. In comparison with the 

 'PS of Central Europe the alpine plants of Norwaj' show a distinct falling oft" 



Fig. 65, I. \'iola calcarata. Lepidopteron- 

 flower ; long-spurred. 2. Viola tricolor. Bee- 

 ilowcr ; short-spurred. Natural size. 



