884 FRUCTIFICATION OF FLOWERS. 



striking instance of the necessity of extraneous 

 intervention to perfect fructification ; male and 

 female flowers are borne on separate trees, and 

 unless the two sorts be in the neighbourhood of 

 each other, the fruit has no kernel and is not 

 proper for food. There was a tree of this kind, 

 bearing female flowers, at Berlin, for the fructifi- 

 cation of which, a branch, with male flowers upon 

 it, was once sent by post from Leipsic, (20 German 

 miles,) and being suspended over some of the 

 pistils, the tree afterwards yielded fruit and seed 

 in abundance. PROFESSOR WILLDENOW has stated 

 a very curious circumstance, concerning the Ari- 

 stolochia Clematitis. He observes that the stamens 

 and pistils of the flower are inclosed in its globular 

 base, the anthers being under the stigma, which 

 thereby requires the intervention of an insect, to 

 convey the pollen to it. The Tipula penni- 

 cornis accomplishes this object; it enters the 

 flower by its tubular part, which is thickly lined 

 with inflected hairs, so as readily to admit the 

 fly, but totally to prevent its release, till by the 

 fading of the corolla the hairs have fallen flat 

 against its sides. Hence the insect in struggling 

 to effect its escape, brushes off the pollen and ap- 

 plies it to the stigma, thereby accomplishing the 

 fertilization of the flower. 



