32 OUR NATIVE ORCHIDS 



which remains adhesive for at least twenty-four hours 

 after the pollen mass has been removed." 



The structure of these discs is the same in Hooker's 

 Orchid as in Hahenaria chlorantha. The stalk of the pollen 

 mass is not attached to the disc directly, but is connected 

 with a little drum-like hinge to which it is fastened at right 

 angles (Plate XIV., Fig. 3). An insect pushing his head 

 between these sticky discs is apt to carry off one or both of the 

 pollen masses, which at first almost stand erect on his head 

 like a pair of horns, and seem, when he enters another 

 flower, to be in danger of hitting against the anther sacs or 

 the discs, and never reaching the stigma. But peep, it you 

 can, at this drum-like hinge under a microscope and you will 

 see a pretty bit of mechanism. The drum contracts or 

 shrinks on the inner under side and pulls the pollen masses 

 down and forward, so that by the end of a few seconds, 

 when the insect is ready to enter another flower, the pollen 

 masses are in the right position to come in contact with the 

 stigma. 



Professor Gray said that he had seen a butterfly in Canada 

 that had a pollen mass of Hahenaria Hookeriana attached 

 to each eye, but as a rule unless a large insect enters this 

 orchid its head is hardly large enough to squeeze between 

 the two discs. But this slight difficulty is overcome by the 

 fact that the lip is curved upward instead of hanging down, 

 and the stigma has a sharp central prominence, so that the 

 flower has the appearance of being divided in half and the 

 insect is generally obliged to approach the nectary in a side- 



