Chap. II. HABENAEIA CHLOEANTHA. 71 



fig. A), above and some way on each side of the stig- 

 matic surface ; if attached in this position to the head 

 of an insect, the insect might visit any number of 

 flowers, and no pollen would be left on the stigma. 

 But observe what takes place : in a few seconds after the 

 inner end of the 'drum-like pedicel has been removed 

 from its embedded position and exposed to the air, one 

 side of the drum contracts, and this . contraction draws 

 the thick end of the poUinium inwards, so that the 

 caudicle and the viscid surface of the disc are no longer 

 parallel, as they were at first, and as they are repre- 

 sented in the section, fig. C. At the same time the 

 drum rotates through nearly a quarter of a circle, and 

 this moves the caudicle downwards, like the hand of 

 a clock, depressing the thick end of the poUinium or 

 mass of pollen-grains. Let us suppose the right-hand 

 disc to be affixed to the right side of an insect's face, 

 and by the tims required^ for the insect to visit 

 another flower on another plant, the pollen-bearing 

 end of the poUinium wiU have moved downwards 

 and inwards, and will now infallibly strike the viscid 

 surface of the stigma, situated in the middle of the 

 flower beneath and between the two anther-cells. 



The little rudimentary tail of the caudicle projecting 

 beyond the drum-like pedicel is an interesting point 

 to those who believe in the modification of species ; 

 for it shows us that the disc has been carried a little 

 inwards, and that primordially the two discs stood even 

 still further in advance of the stigma than they do 

 at present. We thus learn that the parent-form ap- 

 proached in this respect the structure of that extra- 

 ordinary Orchid, the Bonatea speciosa of the Cape of 

 Good Hope. 



The remairkable length of the nectary, containing 

 much free nectar, the white colour of the corspicuous 



