INSECTS AND FLOWERS 195 



of the flower . . . the pollinium is curved and in 

 a state of considerable tension, but retained in 

 that position by a delicate membrane. Now 

 insects alight as usual on the lip of the flower 

 . . . and in front of it are two long processes 

 called antennae. In some species of Catasetum 

 both these antennae are highly irritable ; in the 

 present species (Catasetum saccatum) the right- 

 hand one is apparently functionless; but the 

 moment the insect touches the left-hand one, 

 the excitement is conveyed along it, the mem- 

 brane retaining the pollinium is ruptured, and 

 the latter is immediately jerked out of the 

 flower, by its own elasticity, with considerable 

 force, with the viscid disk foremost, and in such 

 a direction as to come in contact with the head 

 of the insect which had touched the antenna. 

 On subsequently visiting a female flower the 

 insect brings the pollen into contact with the 

 stigma." Here, then, to quote the words of 

 the late Charles Darwin in his historic work on 

 the fertilization of Orchids, "we see a flower 

 patiently waiting with its antennae stretched 

 forth in a well-adapted position, ready to give 

 notice whenever an insect puts its head into the 

 cavity of the labellum. The female Monachan- 

 thus, not having true pollinia to eject, is 

 destitute of antennae. In the male and herma- 

 phrodite forms, namely, Catasetum tridentatum 

 and Myanthus barbatus, the pollinia lie doubled 

 up, like a spring, ready to be instantly shot 

 forth when the antennae are touched. The disk 

 end is always projected foremost, and is coated 

 with viscid matter which quickly sets hard and 



