xi THE SPECIAL COLOURS OF PLANTS 315 



nient which brings them down till they project straight for- 

 ward nearly at right angles to their first position, so as exactly 

 to hit against the stigmatic surfaces of the next flower visited 

 on which they leave a portion of their pollen. The whole of 

 these motions take about half a minute, and in that time the 

 moth will usually have flown to another plant, and thus effect 

 the most beneficial kind of cross-fertilisation. 1 This descrip- 

 tion will be better understood by referring to the illustration 

 opposite, from Darwin's Fertilisatu ' rMek Fi_. 30). 



The Into] station of tin:: Facts. 



Having thus briefly indicated the general character of the 

 more complex adaptations for cross-fertilisation, the details of 

 which are to be foimd in any of the numerous works on the 

 subject,* 2 we find ourselves confronted with the very puzzling 

 question — Why were these innumerable highly complex 

 adaptations produced, when the very same result may be 

 effected — and often is effected — by extremely simple means ? 

 Supposing, as we must do, that all flowers were once of 

 simple and regular forms, like a buttercup or a rose, how 

 did such irregular and often complicated flowers as the 

 papilionaceous or pea family, the labiates or sage family, and 

 the infinitely varied and fantastic orchids ever come into ex- 

 istence ? No cause has yet been suggested but the need of 

 attracting insects to cross fertilise them ; yet the attractive- 

 ness of regular flowers with bright colours and an ample 

 supply of nectar is equally great, and cros -fertilisation can be 

 quite as effectively secured in these by any of the four simple 

 methods already described. Before attempting to suggest a 

 possible solution of this difficult problem, we have yet to pass 

 in review a large body of curious adaptations connected with 

 insect fertilisation, and will first call attention to that portion 

 of the phenomena which throw some light upon the special 

 colours of flowers in their relation to the various kinds of 

 insects which visit them. For these facts we are largely in- 



1 See Darwin's Fertilisation of Orchids for the many extraordinary and 

 complex arrangements in these plants. 



2 The English reader may consult Sir John Lnbbock's British Wild 

 Floicers in Relation to Insects, and H. Mhller's great and original work, The 

 Fertilisation of Floicers. 



