ADAPTATIONS TO HIGH ALTITUDES 57 



are born at a well-advanced state. This case illus- 

 trates in an interesting way how the life histories of 

 animals differ from one another by the lengthening or 

 the shortening of particular chapters. In the Alpine 

 Salamander all the free-swimming or juvenile larval 

 period has been, as it were, telescoped. It has been 

 shunted back into the antenatal period within the 

 mother. 



Mountain light is of greater intensity than lowland 

 light. But light retards the growth of green plants. 

 Perhaps this is part of the explanation of the dwarf- 

 ness and sparse foliage of flowering plants on high 

 mountains. Their stems are short and their leaves are 

 small. Many alpine plants tend to grow like squat 

 cushions. Professor Schimper points out, in his great 

 "Plant Geography," that "the great intensity of light 

 causes the stronger development of certain pigments, 

 especially of anthocyan, in flowers and foliage, 

 whilst on the other hand it causes a more rapid 

 decomposition of the chlorophyll. The richness of 

 mountain light in ultra-violet rays probably favours 

 the development of flowers." Perhaps this is part of 

 the explanation of the large number of flowers and of 

 the intensity of colouring in many alpine plants. Some 

 flowers that are white in the lowlands become brightly 

 coloured in experimental gardens at high altitudes. 

 This is the case with the White Clover (Trifolium 

 rep ens), which becomes deep carmine-red; but it is 

 interesting to remember that there is a rose-purple 

 variety of the plant in the Isles of Scilly. The intensi- 

 fying of colour that follows transplantation to alpine 

 heights has been proved in many cases. Plants grow- 

 ing at high altitudes sometimes show, when compared 



