78 OPHRE^. Chap.il 



nectar and that the flowers are very conspicuous, it 

 is remarkable that they are rarely visited by insects. 

 Mr. Trimen wrote to me in 1864 that he had lately 

 examined seventy-eight flowers, and only twelve of 

 these had one or both pollinia removed by insects, 

 and only five had pollen on their stigmas. He does 

 not know what insects occasionally fertilise the flowers ; 

 but Mrs. Barber has more than once seen a large fly, 

 allied to Bombylius, with the pollinia oiBisa polygnoides 

 attached to the base of its proboscis. Mr. Weale states* 

 that D. macrantha differs from D. grandiflora and earnuta 

 in producing plenty of seed, and is remarkable from 

 often fertilising itself. This follows from " a very slight 

 jerk, when the flower is fully expanded, sufficing to 

 eject the pollinia from their widely open anther-cases, 

 and to bring them into contact with the stigma. 

 This in nature is not unseldom the case, as I have 

 repeatedly found many flowers thus fertilised." He 

 has, however, no doubt that the flowers are likewise 

 cross-fertilised by nocturnal insects. He adds that 

 D. grandiflora in being so seldom fertilised by insects 

 off'ers a case like that of Oplirijs muscifera ; w^hilst 

 D. macrantha in being often self-fertilised closely cor- 

 responds with Ophrijs apifera ; but this latter species 

 seems to be invariably self-fertilised. 



Lastly, Mr. Weale has described,! as far as he could 

 make out, the manner in which a species of Disperis 

 is fertilised by the aid of insects. It deserves notice 

 that the labellum and two lateral sepals of this plant 

 secrete nectar. 



We have now finished with the Ophre?e ; but before 

 passing on to the following tribes, I will recapitulate 



* ' Jonrn. Linn. Soc. Bot.' vol. t * Jomn. Linn Soc. Bot.* vol. 



xiii. 1871. p. 4.^. xiii. 187L p. 42. 



