22 OPHRE.K. Chai'. I. 



but as the flat top curls round the cylindrical and 

 thill proboscis, or round a bristle, the pollinia neces- 

 sarily diverge. As soon as the saddle has clasped the 

 bristle and the pollinia have diverged, a second move- 

 ment commences, which action, like the last, is ex- 

 clusively due to the contraction of the saddle-shaped 

 disc of membrane, as will be more fully described in 

 the ninth chapter. This second movement is the 

 same as that in 0. mascida and its allies, and causes 

 the divergent pollinia, which at first projected at right 

 angles to the needle or bristle (see fig. F), to sweep 

 through an angle of nearly ninety degrees towards the 

 tip of the needle (see fig. G), so as to become de- 

 pressed and finally to lie in the same plane with the 

 needle. In three specimens, this second movement 

 was effected in from thirty to thirty-four seconds after 

 the removal of the pollinia from the anther-cells, and 

 therefore in about fifteen seconds after the saddle had 

 clasped the bristle. 



The use of this double movement becomes evident 

 if a bristle with pollinia attached to it, which have 

 diverged and become depressed, be pushed between 

 the guiding ridges of the labellum into the nectary 

 of the same or another flower (compare figs. A and 

 G) ; for the two ends of the pollen-masses will be 

 found now to have acquired such a position that the 

 end of the one strikes against the stigma on the one 

 side, and the end of the other at the same moment 

 strikes against the stigma on the opposite side. The 

 secretion on tlio stigmas is so viscid that when the 

 pollinia are withdrawn, the elastic threads by which 

 the packets of pollen are bound together are ruptured ; 

 and some dark-green grains may be seen, even by the 

 naked eye, remaining on the two white stigmatic sur- 

 faces. I have shown this little experiment to several 



