Chai . I. FERTILISED BY INSECTS. 29 



and would consequently be rarely visited by insects. 

 I then looked at the perfectly healthy plant under 

 the bell-glass, and it had, of course, all its pollinia iu 

 the anther-cells. I tried an analogous experiment with 

 specimens of 0. mascula with the same result. It de- 

 serves notice that the spikes which had been covered 

 up, when subsequently left uncovered, never had their 

 pollinia carried away by insects, and did not, of course, 

 set any seed, whereas the adjoining plants produced 

 plenty of seed. From this fact it may be inferred 

 that there is a proper season for each kind of Orchis, 

 and that insects cease their visits after the proper 

 season has passed. 



With many of the hitherto mentioned species, and 

 with several other European kinds, the sterility of the 

 flowers, when protected from the access of insects, 

 depends solely on the pollen-masses not coming into 

 contact with the stigma. This has been proved to be 

 the case by Dr. Hermann Miiller, who, as he informs 

 me, applied the pollen-masses of Orchis 'pyramidalis 

 (44), fmca (6), militaris (14), variegata (3), corioplwra 

 (6), morio (4), maculata (18), mascula (6), latifolia (8), 

 incarnata (3), Ophrys muscifera (8), Gj/mnadenia conop- 

 sea (14), alhida (8), Rerminium monorchis (6), Epipogon 

 aplnjllus (2), Epipactis latifolia (14i),pahistris (4), Listera 

 ovata (5), and Cijpripediiim calceolus (2), to their own 

 stj.gmas, and full-sized capsules, containing seeds in 

 appearance good, were formed. The numbers placed 

 after the names of the species show how many flowers 

 were tried in each case. These facts are remarkable, 

 because Mr. Scott and Fritz ]Muller* have proved 



* Aa abstract of their observa- ticalioii,' chap. xvii. 2nd edit. vol. 

 tioris is given in my 'Variation of ii. p. IH. 

 Aiiiriuils and Plants under Douim- 



