186 Mr. W. Murton Holmes on the 
the deflection of the segments, remaining in the different bends 
into which I placed it. No amount of irritation seemed to alter 
its determination to remain for all intents and purposes a twig. 
The first time I touched the insect it remained feigning death 
for a minute and a half, but after worrying it as I have described, 
it remained motionless for nearly five minutes. 
125.—Tur Fertiization or Frowerine Puants: some Mrrnops 
or POLLINATION. 
By W. Murton Houmzs. 
(Read October 15th, 1895.) 
Ir we examine a complete flower, such as that of the almond, 
we find it is composed of four whorls of modified leaves, the 
outer one constituting the calyx, the next in order is the corolla, 
then come the stamens, and the pistil occupying the centre. The 
pistil is made up of one or more carpels, containing the ovules, 
which after fertilization develop into seeds. On the upper part 
is placed the stigma, an expansion of loose tissue covered with 
papilla, or frequently by hairs, generally placed on a kind of 
stalk called the style. When fully developed the stigma secretes 
a sugary fluid, which serves to retain the pollen-grains which 
fall upon it, and subsequently promotes their development. The 
stamens consist of pollen-sacs or anthers placed at the end of 
a stalk called the filament. 
The whole of these parts are not found in all flowers. In 
some cases we have flowers consisting of stamens only, or of 
pistils only, as in the catkins of poplar, willow, oak, and hazel ; 
in others the corolla is absent, and in others there is neither calyx 
nor corolla. 
Pollen-grains are of various sizes and shapes, being globular, 
oval, or angular, and the surface is frequently ornamented by 
spines, or pitted and furrowed in an endless variety of ways. In 
some cases they remain in groups of four, as when first formed, 
and in most orchids the whole of the contents of the pollen-sacs 
remain joined together in masses, termed pollinia. When a 
pollen-grain falls upon the stigma its inner layer protrudes one 
or more tubes, called pollen-tubes, through the outer coat. This 
tube continues to grow through the tissue of the stigma and 
style until it reaches the ovule, which it penetrates, and there 
fuses with the egg-cell, which afterwards develops into the seed. 
In the Gymnosperms, which comprise such plants as firs and 
larches, there is neither ovary nor stigma, and the pollen is 
