8o OUR NATIVE ORCHIDS 



the structure is very similar, the pollen is deposited on the 

 thorax, and such is probably the case in this species. In 

 either case cross fertilisation would be eflFected. Nothing 

 else is possible in the flower, and whether it is Bomlus or not 

 that eflFects it, the method is sufficiently evident." 



Mr. Gibson says: "I have never happened to observe an 

 insect at work upon this flower, but the intention of its 

 structure is so plain that by a mere examination we may 

 safely prophesy, not only what must happen when the insect 

 seeks its nectar, but with equal assurance the kind of insect 

 thus invited and expected. The column is here quite elon- 

 gated, forked at the tip, the space between the forks occu- 

 pied by the anther, which is hinged to the upper division. 

 This anther lid is closed tightly, with the sticky mass of 

 pollen hidden behind it in the cavity. The stigma is on the 

 external inner side of the lower division, and thus distinctly 

 separated from the pollen. The lip is extended forward as 

 a hospitable threshold for the insect. And to what insect 

 might we assume this invitation of colour, fragrance, nectar 

 and threshold to be extended .? 



" Let us consider the flower simply as a device to insure 

 its own cross fertilisation. The insect is welcomed; it must 

 alight and sip the nectar; in departing it must bear away 

 this pollen upon its body, and convey it to the next Arethusa 

 blossom which it visits, and leave it upon its stigma. These 

 are the conditions expressed; and how admirably they are 

 fulfilled we may observe when we examine flower after 

 flower of a group, and find their nectaries drained, their 



