1 68 DIVERSIONS OF A NATURALIST 



others, are examples. Careful study and consideration 

 of the facts have enabled botanists to show, in many 

 instances, within recent years, that the peculiarities of 

 form and also of colour of the stems, leaves, and flowers 

 of plants are not mere unmeaning "accidents," but are 

 definitely of advantage and of "survival value" to the 

 species. Thus we have seen that the tuft-like cushions 

 formed by high Alpine plants are explained. The 

 purple and reddish colour of stalks and leaves like that of 

 the red variety of the common beech has not always, as 

 in that plant, the purpose of protecting the chlorophyll 

 from destruction by too vivid sunlight. In Alpine plants 

 it is often present on the underside of leaves and of the 

 petals, and acts to the plant's benefit, absorbing light and 

 converting it into heat. But it also seems in many cases 

 to protect the juices of the plant from the destructive 

 action of white light. 



It is held by some botanists that the bright colour 

 of Alpine (and Norwegian) samples of a flower elsewhere 

 of a paler colour is due to the direct action of the greater 

 sunlight of the high regions in causing the formation of 

 pigment. This is inadmissible. The sunlight cannot 

 act in that way. It causes increased- formation of 

 nutriment by acting on the chlorophyll, and an Alpine 

 plant thus highly charged with nutritive matters can 

 afford to form more abundant pigment than a plant 

 which enjoys less brilliant sunshine. The high-coloured 

 Alpine flowers are a breed or race ; a pale-coloured 

 plant taken to the Alps from below does not itself be- 

 come high coloured. It is a matter of natural selection. 

 The occasional high-coloured " spontaneous " variations 

 produced from seed have an advantage in the short 

 summer of the high Alps. They attract the visits of 

 the few insects in the short season more surely than do 



