270 BOTANY. 



down into the spur (sp) in search of nectar or sweet juices, 

 in the mean time perhaps resting its feet upon the lip (l). 

 Its head comes in contact with the sticky disks (at h), 

 which adhere tenaciously. When the insect withdraws its 

 tongue, it at the same time carries away the pollen-masses 

 adhering to its head. When the insect visits another 

 Orchid-flower of the same species, the pollen-masses are 

 thrust against the sticky stigma {st) and all or a part 

 adheres to it. Thus, as the insect passes from flower to 

 flower, it unconsciously pollinates them, alwayp, however, 

 carrying the pollen of one flower to the stigma of some 

 other. 



512. The Lady's-slippers are examples of Orchids with 

 tvvo anthers; these are upon the sides of the curved column 

 which bears the stigma higher up. The lip is here shaped 

 like a slipper (whence the common name), into the opening 

 of which the column bends. The lip and the other parts 

 of the perianth are colored, often showing striking 

 contrasts, and these doubtless serve to attract the notice of 

 insects. When an insect enters the slipper (lip), it does so 

 from the top ; but once inside, it finds it diflBcult to escape 

 by that route on account of the incurved margins of the 

 opening, as well as the smooth sides of the slipper. It ac- 

 cordingly passes backward under the dependent stigma, 

 and escapes by squeezing between the column and base of 

 the slipper : in doing this it covers its back with sticky 

 pollen from the anther on the column. When it visits 

 another flower, this experience is repeated; and as it passes 

 under the stigma in its endeavor to find an exit some of 

 the pollen is left on its surface. 



513. Among the tropical Orchids there are some marvel- 

 lous flowers. One of the most remarkable of these is Si 



