MOVEMENTS IN THE ORGANS OE PLANTS 23 
is self-fertilised, the pollinia, when mature, bending forward and 
depositing the pollen on the stigmatic spot of the flower. The 
movement of the pollinia is shown in many more of the British 
orchids, and is visible to the naked eye or with the help of a 
pocket lens, the cause being in most cases hygroscopical. 
The Catasetums and some of the Odontoglots have somewhat 
complicated floral appendages, which assist largely in aiding 
insects in their fertilisation, and it is probable that even hum- 
ming-birds visiting the flowers in search of nectar set moving 
the floral parts connected with the stamen and make it shed 
its pollen on their throats and heads, ready to impregnate the 
next flower visited. Other flowers have a sugar-tongs-like pair 
of anther-lobes which remain closed, retaining the pollen dust ; but 
as soon as any insect enters the flower they open apart, and allow 
the ripe pollen dust to sprinkle the insect. The pollen is, how- 
ever, retained till the anther receives some sort of shock, causing 
the separation of the anther-valves. In Dendyohiim fimhriatum 
there is what may be called an expulsive apparatus, the action 
of which is brought into play by any pressure on the lower 
extremity of the horn or central column, and the stimulus is at 
once transmitted to that part of the rostellum which forms the 
viscid disc, the slightest touch applied to the tip of one of the 
horns being instantly followed by the rupture of the tissue 
and by the consequent liberation of the pollen-masses. The 
viscid disc had, however, in turn sufficed to keep a curved elastic 
band, which serves to attach the disc to the pollinia, on the 
stretch and in its proper position, so that when the disc is set 
free the band flies up and straightens itself with a jerk, by 
which the viscid disc and pollinia are torn from their recesses, 
and are carried in an ample curve away from the column which 
till then served for their common base. 
We have yet to record phenomena of motion which, being 
visible to the naked eye and the result of outside irritation, are 
by far the most interesting. Besides this, they may be seen and 
studied by possessors of small gardens with no glass. The 
Sensitive-plant can be raised from seed in a pot, stood in a 
warm sunny window, first soaking the seeds in warm water, 
and then only lightly covering them with light friable soil ; but 
though this is so very interesting, many quite common garden 
flowers exhibit motion in their stamens and pistils in response 
to a touch or some form of irritation. 
The common barberry, and notably the fine acanthus- 
leaved species named Berberis Bcali, well exhibits this form of 
irritability, for if a needle be passed down into the cup-shaped 
corolla between the anthers and the style, the anthers will at 
once bend forward towards the stigma with a sudden jerk, and 
throw their pollen away from it. The anthers of Kalmia 
latifolia are at first confined in little pits in the walls of the 
corolla, but when an insect visits the flower to rifle its honey, 
alighting on the corolla, the anthers are pulled from their 
