Chap. VII. CATASETUM SACCATUM. 185 



with a slit down one side, like an adder's fang. They 

 are composed of numerous, much elongated, generally 

 hexagonal cells, pointed at both ends ; and these cells 

 (like those in most of the other tissues of the flower) 

 have nuclei with nucleoli. The antennae are prolonga- 

 tions of the sides of the anterior face of the rostellum. 

 As the riscid disc is continuous with a little fringe of 

 membrane on each side, and as this fringe is continuous 

 with the bases of the antennas, these latter organs are 

 put into direct connection with the disc. The pedicel 

 of the poUinium passes, as already stated, between the 

 bases of the two antennse. The antennae are not free 

 for their whole length ; but their exterior edges are 

 firmly united to and blend for a considerable space 

 with the margins of the stigmatic chamber. 



In all the flowers which I examined, taken from 

 three plants, the two antennae which are alike in 

 structure occupied the same relative position. The 

 extreme part of the left-hand antenna bends upwards 

 (see B, fig. 28, in which the position is shown plainer 

 than in A), and at the same time a little inwards, so 

 that its tip is medial and guards the entrance into 

 the cavity of the labellum. The right-hand antenna 

 hangs down, with its tip turned a little outwards ; and 

 as we shall immediately see, is almost paralysed, so as 

 to be functionless. 



Now for the action of the parts. When the left- 

 hand antenna of this species (or either of the antennae 

 in three of the following species) is touched, the edges 

 of the upper membrane of the disc, which are con- 

 tinuously united with the surrounding surface, instantly 

 rupture, and the disc is set free. The highly elastic 

 pedicel then instantly flirts the heavy disc out of the 

 stigmatic chamber with such force, that the whole 

 poUinium is ejected, bringing away with it the two 



