COLOUES OF PLANTS. 



237 



cultivated in Lapland/^ ^ The same writer goes on to 

 say that all the seeds of cultivated plants acquire a 

 deeper colour the further north they are grown, white 

 haricots becoming brown or black, and white wheat 

 becoming brown, while the green colour of all vegetation 

 becomes more intense. The flowers also are similarly 

 changed : those which are white or yellow in central 

 Europe becoming red or orange in Norway. This is 

 what occurs in the Alpine flora, and the cause is said 

 to be the same in both — the greater intensity of the 

 sunlight. In the one the light is more persistent, in 

 the other more intense because it traverses a less thick- 

 ness of atmosphere. 



Admitting the facts as above stated to be in them- 

 selves correct, they do not by any means establish the 

 theory founded on them ; and it is curious that Grisebach, 

 who has been quoted by this writer for the fact of the 

 increased size of the foliage, gives a totally diflerent ex- 

 planation of the more vivid colours of Arctic flowers. 

 He says — We see flowers become larger and more 

 richly coloured in proportion as, by the increasing length 

 of winter, insects become rarer, and their co-operation 

 in the act of fecundation is exposed to more uncertain 

 chances." (Vegetation du Globe, voL i. p. 61 — 

 French translation.) This is the theory here adopted to 

 explain the colours of Alpine plants, and we believe 

 there are many facts that will show it to be the pre- 

 ferable one. The statement that the white and yellow 

 flowers of temperate Europe become red or golden in the 

 Arctic regions must we think be incorrect. By roughly 



^ Revue des Deux Mondes, 1877. " La Vegetation dans les hautes Lati- 

 tudes," jjar M. Tisserand. 



