1 78 VANDE^. Chap. YtL 



CHAPTEE VJl. 



YANDEX continued. — CATAEETID-E 



Catasetidsa, the most remarkable of all Orchidd — The mechanism Bj 

 which the pollinia of Catasetnm are ejected to a distance aud arb 

 transported by insects — Sensitiveness of the horns of the rostellum 

 — Extraordinary difference in the male, female, and hermaphrodite 

 forms of Catasetum tridcutatum — Mormodcs ignea, curious structure 

 of the flowers ; ejection of the pollinia — Mormodes luxata — Oyo- 

 noches ventricosum, manner of fertilisation, 



I HATE reserved for separate description one sub-family 

 of the Vandeae, namely, the Catasetidse, which must, I 

 think, be considered as the most remarkable of all 

 Orchids. 



I will begin with Catasetum. A brief inspection of 

 the flower shows that here, as with most other Orchids, 

 some mechanical aid is requisite to remoTe the pollen- 

 masses from their cells, and to carry them to the 

 stigmatic surface. We shall, moreover, presently see 

 that Catasetum is exclusively a male form; so that 

 the pollen-masses must be transported to the female 

 plant, in order that seed should be produced. The 

 poUinium is furnished with a viscid disc of huge size ; 

 but this, instead of being placed in a position likely 

 to touch and adhere to an insect visiting the flower, is 

 turned inwards and lies close to the upper and back 

 surface of a chamber, which must be called the stig- 

 matic chamber, though functionless as a stigma. There 

 is nothing in this chamber to attract insects ; and even 

 if they did enter it. the viscid surface of the disc could 

 not possibly come into contact with them. 



