THE LONG-SPURRED VIOLET 129 



all over SwitzerLand, between 6,000 and 9,000 feet. 

 It is often so abundant that it forms a regular carpet 

 of flowers of a pale violet-blue colour on the mountain- 

 side. The leaves are toothed. The flowers are 

 exceptionally large for Violets, and possess a very 

 long, slender spiu", in which the honey is stored. 

 Like many other Alpine plants, they are fertilised by 

 butterflies, being specially adapted to this class of 

 insects. The long spur is a device for placing the 

 nectar out of the reach of any other insects except 

 butterflies, which alone possess a sufficiently long and 

 slender tongue or proboscis to penetrate into the spur. 

 This spur is more than |- of an inch in length, and is 

 very narrow, being only about yV of an inch across. 

 Even if the proboscis of some other insect were 

 long enough, the extreme narrowness of the spur 

 would prevent it reaching the nectar. 



The great naturalist, Hermann Mueller, to whom 

 we owe our present knowledge of the fertilisation 

 of Alpine flowers, observed that in the Alps, nine \ 

 different butterflies visited no less than 194 flowers of \ 

 this Violet in the space of 6f minutes. 



The mechanism to ensure cross-fertilisation is 

 otlierwise practically identical with that to be 

 described later in the case of the Field Pansy 

 (p. 160). 



In the High Alpine region, another but similar 

 species, the Mont Cenis Violet {Viola cenisia, Linn.), 

 occurs infrequently. The leaves differ in being quite 

 uncut at their margins. 



