110 NATURE AND LIFE. 



The hue of certain flowers even varies according to the 

 altitude. Thus the corolla of the Anthyllis vulneraria 

 shades down from white to pale red and vivid purple. In 

 general, the vegetation of open, well-lighted places is 

 richer in color and development than that of regions not 

 accessible to the sun. The nelumbium and the bougain- 

 villoea will not thrive in English greenhouses, though 

 heat is abundantly supplied them, but they unfold com- 

 pletely under the clear sky of Montpellier. Some flowers 

 originally white afterward deepen in color by the direct 

 action of light. Thus Cheiranthus cameleo has a flower 

 at first whitish, afterward yellow, and, at last, a violet-red. 

 The Stylidium fruticosum has petals which are pale yel- 

 low at first, and grow pink. The CEnothera tetraptera 

 passes through white, pink, and red colors successively. 

 The flowers of the Gobcea scandens are green the first day, 

 and violet the next. The Hibiscus mutabilis bears a 

 flower which opens at morning with a white hue, and 

 grows red during the day. The flower-buds of the Aga- 

 panthus umbettatus are white when they begin to unclose, 

 and afterward take on a blue tint. If, at the moment of 

 leaving its spathe, the flower is wrapped in black paper, 

 intercepting the light, it remains white, but regains its 

 color in the sun. Edmond Becquerel remarked that if a 

 slip of red flowering crassida is allowed to bloom in a 

 dimly-lighted room, the petals take a tint half yellow, half 

 pink, at the base. Exposure to sunlight for some hours 

 occasions a red tinge in all the corollas of these little flow- 

 ers. If some parts of the plant are protected by a cover- 

 ing of blackened paper, the flowers thus hidden keep the 

 faint color which they had in the dim light of the room. 

 The tints of fruits in the same way develop under the 

 healthy action of daylight, and the rule extends to those 

 principles of every nature which give taste and odor to the 

 different parts of the plant. 



