ASSISTANCE OF INSECTS IN IMPREGNATION. 33? 



Professor Willdenow concerning the Aristo- 

 lochia Ckmatitis, Engl Bot. t. 398. The 

 stamens and pistils of this flower are enclosed 

 in its globular base, the anthers being under 

 the stigma, and by no means commocliously 

 situated for conveying their pollen to it. 

 This therefore is accomplished by an insect, 

 the Tipula pennicomis, which enters the 

 flbwer by the tubular part. But that part 

 being thickly lined with inflexed hairs, though 

 the fly enters easily, its return is totally im- 

 peded, till the corolla fades, when the hairs 

 lie flat against the sides, and allow the carj- 

 tive to escape. In the mean while the insect, 

 continually struggling for liberty, and pacing 

 his prison round and round, has brushed the 

 pollen about the stigma. I do not doubt the 

 accuracy of this account, though I have ne- 

 ver caught the imprisoned Tipula. Indeed 

 I have never seen any fruit formed by this 

 plant. Probably for want of some insect 

 adapted to the same purpose in its own coun- 

 try, the American A rktolochia Sipho, though 

 it flowers plentifully, never forms fruit in our 

 gardens. 



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