190 VANDE^. Chap. VU. 



We may, at least, safely conclude that the anteniiBe, 

 which are characteristic of the genus Catasetum, are 

 specially adapted to receive and convey the effects of 

 a touch to the disc of the poUinium. This causes the 

 membrane to rupture, and the poUinium is then ejected 

 by the elasticity of its pedicel. If we required further 

 proof, nature affords it in the case of the so-called 

 genus Monachanthus, which, as we shall presently see, 

 is the female of Catasetum tridentatum, and it does not 

 possess poUinia which can be ejected, and the antennae 

 are here entirely absent. 



I have stated that in G. saccatum the right-hand 

 antenna invariably hangs down, with the tip turned 

 slightly outwards, and that it is almost paralysed. I 

 ground my belief on five trials, in which I violently 

 hit, bent, and pricked this antenna, and this produced 

 no effect ; but when immediately afterwards the left- 

 hand antenna was touched with much less force, the 

 poUinium was shot forth. In a sixth case a forcible 

 blow on the right-hand antenna did cause the act of 

 ejection, so that it is not completely paralysed. As 

 this antenna does not guard the labellum, which in all 

 Orchids is the part attractive, that is to insects, its 

 sensitiveness would be useless. 



From the large size of the flower, more especially 

 of the viscid disc, and from its wonderful power of 

 adhesion, I formerly inferred that the flowers were 

 visited by large insects, and this is now known to be 

 the case. The viscid matter sticks so firmly after if 

 has set hard, and the pedicel is so strong (though very 

 thin and only one-twentieth of an inch in breadth at 

 the hinge), that to my surprise a poUinium attached 

 to an object supported for a few seconds a weight of 

 1262 grains, or nearly three ounces ; and it supported 

 for a considerable time a slightly less weight. Whon 



