C N T E N T S. 



ISTRODUCTIOX PogCS 1-5 



CHAPTER I. 



OPHRE^. 



Structure of the flower of Orchis mascuhi — Power of movement of 

 the poUinia — Perfect adaptation of the parts in Orchis pyra- 

 midalis — Other species of Orchis and of some closely allied 

 genera — On the insects which visit the several species, and on 

 the frequency of their visits — On the fertility and sterility of 

 various Orchids — On the secretion of nectar, and on insects 

 being purposely delayed in obtaining it 6-44 



CHAPTER II. 



ophre/t; — continued. 



Fly and Spider Ophrys — Bee Ophrys, apparently adapted for 

 perpetual self-fertilisation, but with paradoxical contrivances for 

 intercrossing — Henninium monorchis, attachment of the pol- 

 linia to the front legs of insects — Peristylus viridisj fertilisation 

 indirectly effected by nectar secreted from three parts of the 

 labellum — Gymnadenia conopsca, and other species — Habenaria 

 or Platanthera chlorantha and bifolia, their po'linia attached to 

 the eyes of Lepidoptera — Other species of Habenaria — Bonatea 

 — Disa — Summary on the powers of movement in the poUinia 



45-79 



