MIMULUS SMITHII. 
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the stamens are spread out renders them incapable, without some assistance, of 
casting their pollen on the head of the stigma. When an insect enters the flower 
in search of honey, and its legs or body touch the inner part of each filament near 
the bottom, which it cannot well avoid, the filaments immediately contract; each of 
them bending over, strikes its head against the top of the stigma, where it deposits 
the pollen, and by this means imprisons the insect. Its confinement, however, is 
seldom of long continuance, for, after a time, some degree of exhaustion appears to 
take place, and the stamens become partially flaccid, of which circumstance the 
insect generally takes advantage and makes its escape. After this the stamens fall 
back to their usual situation, and shortly recover their irritability, which continues 
not merely whilst the anthers are discharging their pollen, but extends more or less 
beyond even the falling of the corolla. No remarkable movement of the stamina 
takes place on touching them in any other part than the inner near the bottom. 
The stamens of Opuntia Tuna, a South American plant, introduced in 1731, is 
endued with a similar irritability, but the stamens do not form so compact a prison 
as Berberis. Another plant, the produce of our British woods, presents also a very 
curious structure — the Aristolochia clemaiitis ; of this plant, which is so curiously 
formed. Professor Willdenow asserts that the anthers, of themselves, cannot impreg- 
nate the stigma. The throat of the flower is lined with thick hair or bristles, 
pointing downwards, so as to form a funnel similar to the entrance into a wire 
mouse-trap. The insects may very easily walk in, but are totally unable to return, 
in consequence of the points of the hairs meeting them. It sometimes happens 
that several enter into one flower, where, their confinement becoming irksome, they 
keep constantly moving about, and thus stimulating the filaments, the anthers 
deposit the pollen upon the stigma ; but, after impregnation is performed, the hair 
shrinks, becomes flaccid, hangs down close by the sides of the flower, and the little 
prisoners then leave their cage. The insect that frequents this plant is a species of 
gnat ( Cecidomia ), although a writer in the Annual Medical Review doubted the 
accuracy of the fact ; but it has since been proved, by ocular demonstration, the 
flowers inclosing the very insects having been sent several miles. 
