354 IMPREGNATION OF THE SEED. CHAP. VII. 



stiff hairs pointing downwards. The globular part 

 contains the pistil, which consists merely of a 

 germen and stigma together with the surrounding 

 stamens. But the stamens being shorter than even 

 the germen, cannot discharge the pollen so as to 

 throw it upon the stigma, as the flower stands 

 always upright, till after impregnation. And hence 

 without some additional and peculiar aid the pollen 

 must necessarily fall down to the bottom of the 

 flower. Now the aid that nature has furnished in 

 this case is that of the agency of the Tipula penni- 

 cornis, a small insect, which, entering the tube of 

 the corolla in quest of honey, descends to the 

 bottom and rummages about till it becomes quite 

 covered with pollen ; but not being able to force its 

 way out again owing to the downward position of 

 the hairs, which converge to a point like the wires 

 of a mouse-trap, and being somewhat impatient of 

 its confinement, it brushes backwards and forwards 

 trying every corner till after repeatedly traversing 

 the stigma it covers it with pollen sufficient for its 

 impregnation ; in consequence of which the flower 

 soon begins to droop, and the hairs to shrink to the 

 side of the tube, effecting an easy passage for the 

 escape of the insect.* 



In monoe- Monoecious plants are, according to Spregnel, 



mostly impregnated by insects also, excepting such 



as are destitute of nectaries. But many of them 



do not require that aid, in which case the male arid 



* Wilklcnow, p. 317. 



