CuAP. IX. SECRETION OF NECTAE. 269 



curious square viscid disc to become securely cemented 

 to an insect's head or body. 



As in Epipactis the cup at the base of the labellum 

 serves as a nectar-receptacle, I expected to find that 

 the analogous cups in Stanhopea, Acropera, &c., would 

 serve for the same purpose ; but I could never find 

 a drop of nectar in them. According, also, to M. 

 Meniere and Mr. Scott * this is never the case in these 

 genera, or in Gongora, Cirrhsea, and many others. In 

 Catasetum tridentatum, and in the female form Mona- 

 chanthus, we see that the upturned cup cannot 

 possibly serve as a nectar-receptacle. What then 

 attracts insects to these flowers ? That they must bo 

 attracted is certain ; more especially in the case of Cata- 

 setum, in which the sexes stand on separate plants. In 

 many genera of Vandeee there is no trace of any nectar- 

 secreting organ or receptacle ; but in all these cases 

 (as far as I have seen), the labellum is either thick and 

 fleshy, or is furnished with extraordinary excrescences, 

 as in the genera Oncidium and Odontoglossum. In 

 Phalasnopsis grayidiflora there is a curious anvil-shaped 

 projection on the labellum, with two tendril-like pro- 

 longations from its extremity which turn backwards 

 and apparently serve to guard the sides of the anvil, so 

 that insects would be forced to alight on its crown. 

 Even in our British Cephalanthera grandiflora, the 

 labellum of which never contains nectar, there are 

 orange-coloured ribs and papillae on the inner surface 

 which faces the column. In Calanthe (fig. 26) a cluster 

 of odd little spherical warts projects from the labellum, 

 and there is an extremely long nectary, which does 

 not include nectar ; in Eidophia viridis the short nec- 

 tary is equally destitute of nectar, and the labellum 



* 'Biillctin Bot. S.;c. de Franco,' toin. il. 1855, p 352. 



