54 THE FERTILISATION OF FLOWERS. [CHAP. 



parts of the flower are highly sensitive, and when 

 touched by a bee convey the impression to the pol- 

 linia which ruptures the confining membrane and 

 hurls the pollinia at the bee, striking it and adhering 

 to it where, on visiting another flower, they come in 

 contact with the stigma. 



The various methods by which fertilisation is 

 effected in the Orchids is in fact more marvellous 

 than in any other genus. " The complication and 

 ingenuity of these contrivances almost exceed belief. 

 ' Moth-traps and spring-guns set on these grounds ' 

 might be the motto of the Orchids. There are baits 

 to tempt the nectar-loving Lepidoptera with rich 

 odours exhaled by night and lustrous colours to shine 

 by day ; there are channels of approach along which 

 they are surely guided, so as to compel them to pass 

 by certain spots ; there are adhesive plasters nicely 

 adjusted to fit their probosces or to catch their 

 brows ; there are hair-triggers carefully set in their 

 necessary path, communicating with explosive shells 

 which project the pollen stalks with unerring aim 

 upon their bodies. There are, in short, an infini- 

 tude of adjustments, for an idea of which I must 

 refer my readers to Mr. Darwin's inimitable powers 

 of observation and description adjustments all con- 

 trived so as to secure the accurate conveyance of the 

 pollen of the one flower to its precise destination in 

 the structure of another."* 



In the common yellow Flag (Iris psendacorns) three 

 of the perianth segments are large and arched over, 

 so as to form a platform, similar to the labellum of 



* Duke of Argyll, " Reign of Law," p. 38. 



