A FEW NATIVE ORCHIDS 1 89 



pollen was withdrawn on the insect's head, and it 

 might be so withdrawn, but in other allied orchids 

 of the tribe Arethusse, however, in which the 

 structure is very similar, the pollen is deposited 

 on the thorax, and such is probably the fact in 

 this species. In either case cross -fertilization 

 would be effected. Nothing else is possible in 

 the flower, and whether it is Bombus or not that 

 effects it, the method is sufficiently evident. 



Having thus had one initiation into this most 

 enticing realm of riddles, each successive orchid 

 whose structure we examine from this stand-point 

 becomes a most interesting, perhaps a fresh, prob- 

 lem, whose assumed solution may often be veri- 

 fied by studying the insect in its haunts. Dar- 

 win thus foretold the precise manner of the 

 cross-fertilization of Habcnaria mascula, and also 

 the insect agent, simply by the structural prophe- 

 cy of the flower itself. 



Suppose, for example, an unknown orchid blos- 

 som to be placed in our hands. Its nectary tube 

 is five inches in length, and as slender as a knit- 

 ting-needle. The nectar is secreted far within its 

 lip. The evolution of the long nectary implies 

 an adaptation to an insect's tongue of equal 

 length. What insect has a tongue five inches 

 long, and sufficiently slender to probe this nee- 



