II COLOUR-VARIATION 55 



which determine variegations are themselves not 

 known ; but the facts are numerous, well authenti- 

 cated, and must be taken into account. Climate 

 certainly has some influence on the colour of flowers, 

 and although we do not exactly know yet what we 

 mean when we speak of differences of climate, as 

 Naudin aptly remarks, and though climate includes a 

 large number of very different factors which are 

 combined in different proportions according to 

 localities, there are influences which may be ascribed 

 to it, /;/ toto. G. Bonnier and C. Flahault have per- 

 formed interesting experiments on this point. G. 

 Bonnier 1 has compared flowers of the same species 

 and age, from different altitudes, in the Austrian Alps 

 and Carpathians, and the result has been that while 

 some plants, such as Rosa alpina and Erigeron alpinus, 

 have the same colour at different heights, others are 

 slightly different : such is the case with TJiymus 

 serpyllum and Geranium sylvaticum ; others are very 

 different, such as Myosotis sylvatica, Campanula ro- 

 tundifolia, Ranunculus sylvaticus, Galium cruciatum. 

 Of course the colour is not radically changed 

 a pink flower does not become yellow, but it 

 grows deeper and richer in plants of higher altitude. 

 Microscopical investigation shows that the pigment 



1 De la Variation avec F Altitude des Matieres colorees dcs Fleurs chez 

 line menu Espcce vegelale. Bull Soc. Botanique, 1880, . 103. 



