434 



HUTCHINSON'S POPULAR BOTANY 



instantly adhere to the intruding object, and when the insect withdraws 

 its head, the two pollinia are seen to be sticking up upon it like a pair 

 of clubbed horns. Moreover, the cement, which has remained viscid under 

 its membranous covering perhaps for many hours, now hardens with great 

 rapidity a wonderful and indispensable provision, for were the pollinia to 

 fall sideways or backwards, their usefulness for purposes of cross-fertiliza- 

 tion would be at an end. Never- 

 theless, at their present angle they 

 are equally useless, for, on visiting 

 another flower, what can happen 

 but that the insect will push them 

 back into their old position ? This 

 danger is obviated by a beautiful 

 contrivance, which Darwin thus 

 explains : " Though the viscid sur- 

 face remains immovably affixed, the 

 apparently insignificant and minute 

 disc of membrane to which the 

 caudicle adheres is endowed with a 

 remarkable power of contraction . . . 

 which causes the pollinium to sweep 

 through about ninety degrees, al- 

 ways in one direction viz., towards 

 the apex of the proboscis in the 

 course on an average of thirty 

 seconds. . . . Now, after this move- 

 ment and interval of time (which 

 would allow the insect to fly to 

 another flower) . . . the thick end 

 of the pollinium is exactly in 

 position to strike the stigmatic 

 surface." Surely if evidence were 

 wanted for the argument of Design 

 in Nature, you have it here ! We 

 may add that Darwin is speaking 

 of the Purple Orchis (0. mascula') ; 

 but his remarks apply equally to 



the^ Spotted Orchis.* The plants are closely related, and the manner of 

 their pollination is the same in all essentials ; indeed, throughout the genus 

 Orchis, but little variation of the organs will be found. 



The genus Orchis is not the only group of orchideous plants containing 

 species which are unprovided with true nectaries. The wonderful Catasetum 



* Indeed, to two other British Orchids -viz., the Green-winged Orchis (0. morio) and the 

 Marsh Orchis (0. latifolia). 



Photo by] 



FIG. 537. PURPLE ORCHIS (Orchis mascula). 



An early spring Orchis with red-purple flowers whose arrange- 

 ments for pollination are very similar to those of the Spotted 



