[152]

a)

But all these appliances are subordinate to the action of insects. Without their aid not one plant in this Tribe, in the 24 genera examined would set a seed. It is also evident that insects would withdraw

[Orchids, p. 210: "But all these appliances are subordinate to the action of insects. Without their aid, not a plant in this tribe, in the twenty-four genera examined, would set a seed. It is also evident that, in a vast majority of cases, insects would withdraw the pollinia only when retreating from a flower, and, carrying them away, would thus effect a union between two distinct flowers. This fact is conclusively shown in all those many cases in which the pollinia undergo a change of position, after removal from the rostellum, in order to stand in a proper direction to strike the stigma; for this could only be effected after the insect had left one flower, which would serve as the male, and before it visited a second flower, which would serve as the female."]