GYROSTACHYS lor 



limit the bees' entrance except just over the tiny hanging 

 lip, and then the column is pressed so low against it that 

 her proboscis can only just be thrust in. So small is the lip 

 that no bee coitld use it as a threshold; it merely serves as a 

 little sign to its visitors of the path to the nectaries (see 

 Plate XXXVI). 



A proboscis one-third of an inch long would be able to 

 reach the storehouse of this orchid's sweets, but the bees 

 seem to do the most thriving business in honey, and never 

 despise these minute orchids that have no silken chambers. 

 Three different species have been seen visiting them, Bom- 

 bus Americanorum, Calltopsis andreniformis, and, in Florida, 

 Megachile brevis. "The last-mentioned insect," said Rob- 

 ertson, who had been watching it in its visits to the Slender 

 Lady's-Tresses, "was found with two boat-shaped discs 

 with attached pollen masses fastened to the maxillary 

 laminae," in such a manner that when the proboscis was 

 folded up, during the bee's flight from one spike to another, 

 the pollen masses would not be disturbed, but the moment it 

 thrust its proboscis into a fully opened flower, they would 

 come right against the stigma. 



Nothing could be more exquisitely adjusted than the 

 mechanism of this almost infinitesimal flower, for when after 

 its pollen masses have been removed (Fig. i), the whole 

 column rises, as is shown in the illustration of the flower of 

 the Slender Lady's-Tresses in Plate XXXVI. , and presents the 

 sticky surface of the stigma (Fig. 2) in just the right position 

 to receive the vital touch of the pollen. 



