INTRODUCTION 



of certain insects, one must at the same time find it not improbable that there 

 should be some provision for preventing this nectar from being spoiled by rain, 

 and that these hairs may have been placed here for the attainment of this purpose. 

 ... In the following summer I investigated the forget-me-not {Myosoiis palusiris). 

 I found not only that this flower has nectar, but also that the nectar is completely 

 protected against rain. At the same time, however, I was struck by the yellow ring, 

 which surrounds the opening of the corolla tube, and which is so beautifully conspicuous 



yymt 



M,A^ 



XMI i. 



XW * 



JiV".' 



200 jr 



Fig. I. Reduced title-page of Sprengers book, taken from the edition edited by Knuth (in ' Klassiker 

 der exakten Naturwissenscliaften,' vols, xlviii-li). 



against the sky-blue colour of the limb. Might not, I thought, this circumstance 

 also have some reference to insects? Might not Nature have specially coloured 

 this ring, to the end that it might show insects the way to the nectar reservoir? 

 With this hypothesis in view, I examined other flowers, and found that most of 

 them confirmed it. For I saw that flowers, in which part of the corolla is 

 differently coloured from the rest, always have spots, figures, lines, or dots of 

 peculiar hue just where the entrance to the nectar reservoir is situated. I now 



