Chap. VII. 



CATASETUM. 



191 



the pollinium is shot forth, the large spike-like anther 

 is generally carried with it. If the disc strikes a flat 

 surface like a table, the momentum from the weight 

 of the anther often carries the pollen-bearing end 

 beyond the disc, and the pollinium is thus affixed in 

 a wrong direction for the fertilisation of another 

 flower, supposing it to have been attached to an 

 insect's body. The flight of the pollinium is often 

 rather crooked. * But it must not be forgotten that 

 under nature the ejection is caused by the antennae 

 being touched by a large insect standing on the la- 

 bellum, which will thus have its head and thorax 

 placed near to the anther. A rounded object thus 

 held is always accurately struck in the middle, and 

 when removed with the pollinium adhering to it, the 

 weight of the anther depresses the hinge of the pol- 

 linium ; and in this position the anther-case readily 

 drops off, leaving the balls of pollen free, in a proper 

 position for fertilising the female flower. The utility 



* M. Baillon (• Bull, de la Soc. 

 Bot. de France,' torn. i. 1854, p. 

 285) states that Gatasetum luridum 

 ejects its pollinia always in a 

 straight line, and in such a direc- 

 tion that it sticks fast to the 

 bottom of the concavity of the 

 labellum ; and he imagines that 

 in this position it fertilises the 

 flower in a manner not clearly 

 explained. In a subsequent paper 

 in the same volume (p. 367) M. 

 Me'niere justly disputes M. Bail- 

 Ion's conclusion. He remarks 

 that the anther-case is easily de- 

 tached, and sometimes naturally 

 detaches itself ; the pollinia then 

 swing downwards by the elasticity 

 of the pedicel, the viscid disc still 

 remaining: attached to the roof 

 of the stigmatic chamber. M. 

 Meniere hints that, by the subse- 



quent and progressive retraction 

 of the pedicel, the pollen-masses 

 might be carried into the st'gmatic 

 chamber. This is not possible in 

 the three species which I have 

 examined, and would be uselej^s. 

 But M. Meniere himself then goes 

 on to show how important insects 

 are fur the fertilisation of Orchids ; 

 and apparently infers that their 

 agency comes into play with 

 Catasetum, and that this plant 

 does not fertilise itself. Both INI. 

 Baillon and M. Me'niere correctly 

 describe the curved position in 

 wliicli the elastic pedicel lies 

 before it is set fiee. Neither of 

 these botani.-ts seenis to be aware 

 that the species of Catasetijin 

 (at lea^t the five which I have 

 examined; are exclusively mole 

 plants. 



