i ;6 SPIDER, MUSK, BUTTERFLY ORCHIS. [CHAP. 



has met with very few cases in which the pollen mass 

 failed to reach its own stigma. He has never seen 

 an insect visit the flowers of this species, and R. 

 Brown suggested that the resemblance of the flower 



OO 



to bees was to deter insects from visiting them. 

 Darwin does not think this probable. He believes 

 also that, though this species habitually fertilises 

 itself, the curious arrangements which it possesses 

 in common with other allied species, are of use in 

 securing an occasional cross, even if only at very 

 long intervals. 



OpJirys arachnites is by some botanists (for instance 

 by Bentham) regarded as a mere variety of O. 

 apifera, but the stalks of the pollen masses are not 

 much more than half as long, without any diminution 

 of thickness. In proportion, therefore, and in their 

 stiffness, they more nearly resemble the other section 

 of the group. Mr. Moggridge, however, has found 

 at Mentone intermediate forms, not only between 

 O. arachnites and O. apifera, but also between 

 these, O. aranifera and O. Scolopax. O. arachnites 

 and O. apifera do not in England appear liable to 

 pass into one another. 



In the Musk orchis (Herminium monorchis), the 

 stalks of the pollen masses are short, and the disks 

 large. This species does not produce honey, but has 

 a strong odour, especially at night. 



Habenaria chlorantha (the Large Butterfly orchis) 

 has both a sweet scent and honey. It is much fre- 

 quented by insects. The anther cells are widely 

 separated ; the pollinia slope backwards, and are 

 much elongated ; the viscid disk is circular, prolonged 

 on its imbedded side into a short, drum-like pedicel. 



