Just within the corolla the third part or set appears, consisting of six _stamens_. These six stamens are also in two sets of three each, an outer and an inner one. Each stamen consists of a long stalk-like part, called the _filament_, and at the summit of the filament is borne the _anther_, which in the lily consists of two long, narrow pouches lying side by side. When the anther is ripe these pouches are filled with a yellow, powdery dust called the _pollen_. Each particle of this dust-like pollen consists of a minute, but beautifully organized globular body, known as the _pollen-grain_. The anther pouches are therefore full of pollen-grains. [Illustration: RED OR WOOD LILY. (Lilium Philadelphicum)] In the lily it will be noticed that when the anthers are ripe and the pollen is ready to be shed, a slit opens lengthwise in each of the two pouches or sacs. This is the common method for opening the anther sacs, but in some flowers it is curiously modified. For example, in the heaths, such as the huckleberry, the sacs open by a hole at one end, and sometimes the tips of the sacs are drawn out into long, hollow tubes through which the pollen is discharged. In other cases, as in the sassafras, the sacs open by little trap doors, which swing open as if upon hinges. Of the two parts of the stamen, the filament and anther, the latter is the essential one, so that in some cases the filament may be lacking entirely, only the anther appearing to represent the stamen. Furthermore, the essential thing about the anther is the pollen, to manufacture which is the sole purpose of the stamen. The pollen is necessary to enable the flower to produce seeds, but it must be transferred from the anther which produces it to the fourth part of the flower, not yet described, in which the seeds are formed. This transfer of pollen is known as _pollination_, and the transfer is usually effected in one of two ways, by the wind or by insects. As a rule, also, the pollen made by one flower must be transferred to some other flower to do its work, and sometimes the other flower may be at a considerable distance. If the pollen is to be transferred by the wind it must be very light and dry, and it must also be very abundant, for the wind is a chance carrier and drops the pollen everywhere in a very wasteful fashion. In such a case the pollen must come down like rain to be sure that some of it strikes the right spot in the right flowers. Occasionally one hears in the papers of "showers of sulphur," which always prove to be showers of pollen carried by the wind from some forest (chiefly evergreen forests) and dropped at random. In the case of pines the minute pollen grains develop wings to assist in the wind transportation.