COLOURS OF FLOWERS. 177 



has often been noticed ; and when plants growing near Paris 

 were transfen^ed to a much higher latitude, the flowers 

 deepened in colour. This, however, is thought not to be due 

 to a clearer atmosphere, but to the enhancement of the foliage, 

 as M. Ch. Flahault showed that the leaves of plants of the 

 same species are larger in proportion as the latitude is 

 higher, the comparatively large dimensions being due to the 

 duration of light of a relatively feeble intensity. Flowers 

 being dependent upon leaves, great importance must be 

 attached to tbe power of the latter to store up nutriment for 

 them. Thus, in the case of Hyacinths both blue and red, 

 M. Flahault found no difference in the colour of the flowers 

 when grown in the light or in the dark, the colour being at 

 the expense of the material stored up in the bulbs. Other 

 experimenters have found that, while some flowers show no 

 difference, others do ; thus Askenazy found no difference in 

 Tulips and Crocuses, though the leaves were etiolated in the 

 dark. With Hyacinths, however, contrary to Flahault, he 

 found that light exerted a two-fold influence, an acceleration 

 of at least a fortnight in flowering and a much more intense 

 a.nd more diffused colour ; those in darkness being only 

 tinged where the uncoloured ones where darkest. Pulmonaria 

 officinalis in darkness changed from red to blue, as usual ; 

 but in proportion as the buds were in a less advanced stage 

 when placed in darkness, so were the colours fainter. His 

 conclusion is that some flowers require light to develop their 

 normal colours, while others are independent of it.* Mr. 

 Sorby t agrees with Askenazy ; and concludes that the arrest 

 of normal development in darkness varies with the nature 

 of the colouring matters, the effect being greater with the 

 more easily decomposable substances, " Those substances 

 which when dissolved out from the petals are the most easily 



♦ Bot. Zeit, Jan., April, 1876. t Nature, April 13, 1876. 



N 



