Fertilization of Flowering Plants. 198 
gets covered with pollen, which is deposited on the stigma of the 
next flower visited. 
Some flowers, such as the barberry, have irritable stamens, so 
that when the lower part of the filaments are touched by insects 
attracted by honey the anther is caused to strike against them, 
and cover them with pollen. 
Where the period of vegetation is very short, and the weather 
frequently bad, as in high latitudes or on mountains, such plants 
that can fertilize themselves will be more sure of ripening their 
seeds than such that must wait for insects, more especially as 
under these conditions insects are themselves scarce. A similar 
condition obtains in the desert. The Rey. G. Henslow, reporting 
on desert flowers, says that flowers that have been adapted to 
insects, and therefore endowed with conspicuous and _bright- 
coloured, often irregular corollas, honey, and other details, have 
to a great extent lost these by a degenerating process. 
Although cross-fertilization is aimed at, there are many con- 
trivances to bring about self-fertilization in the case of failure— 
by the movements of the stamens, by the elongation and bending 
of the pistil, by the bending back of the style-branches, by the 
opening and closing of the corolla, by movements of the flower- 
stalk, or by co-operation of several movements. 
In Senecio viscosus the style-branches are furnished at the lip 
with a bundle of collecting-hairs. As the style elongates these 
hairs sweep the pollen out of the anther-tubes, and leave it in a 
lump at the top of the tube, whence it may be carried off by 
insects. Soon afterwards the two style-branches, which have 
undergone rapid elongation, part asunder, and the pollen, if not 
already removed by insects, is shaken off, and falls on to the 
pappus-hairs, where it is caught by the barbs on their surface. 
The stigmatic tissue on the inner faces of the style-branches, 
which are now the upper surfaces, are in a position to get dusted 
with pollen brought by insects from other flowers. Meanwhile 
an elongation of every part of the flower has taken place, and 
the flower enters upon its third stage of development. The two 
style-branches curve down, and bring the stigmatic tissue into 
contact with the pollen sticking to the pappus-hairs, which now 
reach above the arms of the style. 
In fool’s-parsley the pistils are first developed before the 
corolla is expanded. The stamens are folded at the five corners 
of the flower-bud, and straighten out when the flower opens, 
finally bending inwards over the stigmas, on which they let fall 
their pollen. 
The cases that I have brought to your notice will serve as 
examples of some only of the methods whereby fertilization is 
brought about. Probably every flower has some method more 
or less specially adapted to its requirements. We have seen 
