194 IRRITABLE PARTS OF FLOWERS. 



ment, unaffected by external causes. The five fila- 

 ments of the Cock's-comb, are connected at their lower 

 part by a membranous web, which in moist weather is 

 relaxed, and the stamens spread for shelter under the 

 concave lobes of the corolla. When the air is dry, the 

 contraction of the membrane brings them together, to 

 scatter their pollen in the centre of the flower. The 

 elastic filaments of Parietaria, for a while restrained 

 by the calyx, as those of the lovely Kalmia, are by the 

 minute pouches in the corolla, relieve themselves by 

 an elastic spring, which in both instances serves to dash 

 the pollen with great force upon the stigma. 



But of all the flowers, that of the Barberry-bush is 

 most worthy the attention of a curious physiologist. In 

 •his the six stamens, spreading moderately, are shel- 

 tered under the concave tip of the petals, till some ex- 

 traneous body, as the feet or trunk of an insect in search 

 of honey, touches the inner part of each filament near 

 the bottom. The irritability of that part is such, that 

 the filament immediately contracts there, and conse- 

 quently strikes its anther, full of pollen, against the 

 stigma. Any other part of the filament may be touched 

 without this effect, provided no concussion be given to 

 the whole. After a while the filament retires gradually, 

 and may again be stimulated , and when each petal, with 

 its annexed filament, is fallen to the ground, the latter 

 on being touched shows as much sensibility as ever. 



I have already mentioned that any moisture causes 

 the pollen to explode, consequently its purpose is lia- 

 ble to be frustrated by rain or heavy dews. Linnaeus 

 observes that husbandmen find their crops of rye to suf- 

 fer more from this cause than barley, because in the 

 latter the anthers are more protected by the husks ; and 

 the Juniper-berries are sparingly, or not at all, pro- 



