APRIL 71 



purple to blue, pure blue being the rarest of all colours 

 in flowers, nearly all blue corollas containing a tinge of 

 red. This sequence may be observed in those flowers 

 which pass through several colours in the course of 

 blooming, as do so many of the Borage family, e.g. 

 viper's bugloss, lungwort, and forget-me-not. An 

 extreme case is the little annual Myosotis versicolor, 

 whereof the flowers open pale yellow, become pink, and 

 pass off blue. 



All this, however, does not account for the produc- 

 tion of white flowers, which probably outnumber those 

 of any other hue. Mr. Allen surmised that the most 

 primitive form of petalled flower is that in which ' the 

 carpels exist in a separate form, instead of being united 

 in a single compound ovary.' In such flowers, whereof 

 he took the common cinquefoil or Potentilla reptans 

 as a type, he considered that the original hue was 

 yellow; but that as plants somewhat higher in the 

 scale were evolved, there was a tendency towards white 

 and pink blossoms, as in the strawberry and the rose. 

 Account must also be taken of the tendency of very 

 many coloured species to produce white 'sports.' 

 White flowers are more conspicuous than any others ; 

 any approach to white in a blossom would attract insect 

 visitors even more surely than the primitive yellow or 

 the more advanced red, thereby securing the fertilisa- 

 tion of a preponderance of white or pale flowers, and 

 the establishment of a white-flowering race in substitu- 

 tion for or addition to the ancestral colour. One is 

 accustomed to assume that the red-flowered hawthorn 

 i.e the natural variety, not the outcome of the 



