178 VANDE^. Coat, VII. 



CHAPTEE yn. 



VANDE^ continued. — OATASElTDiE 



CatasetidsB, the most remarkable of all Orchids — ^The mechanism ty 

 which the pollinia of Oatasetum are ejected to a distance and are 

 transported by insects — Sensitiveness of the horns of the rostellum 

 — Extraordinary difference in the male, female, and hermaphrodite 

 forms of Oatasetum tridentatum — Mormodcs ignea, curious structure 

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

 noches ventricosum, manner of fertilisation. 



I HAVE reserved for separate description one sub-family 

 of the Vandese, namely, the Catasetida3, which must, I 

 think, be considered as the most remarkable of all 

 Orchids. 



I will begin with Oatasetum. A brief inspection of 

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

 some mechanical aid is requisite to remove the pollen- 

 masses from their cells, and to carry them to the 

 stigmatic surface. We shall, moreover, presently see 

 that Oatasetum 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 

 pollinium is fuj^nished 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. 



