POLLINIUM

I5I9

POLITICAL PARTIES

sects. The plants which use wind as a carrier of pollen are called anemophilous plants; those which use insects for this purpose are called entomophilous. The gymnosperms and many of the more primitive angiosperms, as grasses and many of the common trees, are anemophilous. The great majority of angiosperms are entomophilous, and their flowers have been modified in everyway to be adapted to insect-visits, and the insects have been variously adapted to flowers. For anemophilous pollination see Gymnosperms. Entomophilous pollination is of two kinds : namely, self-pollination, in which the pollen is transferred to the stigma of its own flower; and cross-pollination, in which the pollen is transferred to the stigma of some other flower. In the case of cross-pollination the two flowers concerned may be upon different plants which may be quite distant from one another. The advantage of this relation to the insects is to secure food. This the flower provides either in the form of nectar or pollen, and the insects which pollinate flowers may be roughly divided into the two groups of nectar-feeding insects, represented by butterflies and moths, and the pollen-feeding insects, represented by bees, wasps etc. The presence of these food-supplies is made known to the insect by odor, form and, perhaps, color of flowers. Those insects which are suitable for this ! work are necessarily flying forms, as creeping insects would brush off the pollen from their bodies in passing from one flower to another. Plants have many devices by which such unsuitable creeping insects as ants may be warded off. Just what the advantage of cross-pollination over self-pollination may be is not clear, but that it is of great advantage is evident from the fact that the angiosperms have made most elaborate attempts to secure it. In most insect-pollinating flowers there are three problems: To hinder self-pollination; to secure the visits of suitable insects; and to ward off the visits of unsuitable insects. Most of the insect-pollinating flowers may fall into three great divisions on the basis of the methods they use to hinder self-pollination. The first division includes those flowers in which the pollen and stigma are so related to each other in position that the pollen is not likely to fall upon the stigma. This method results in much of the irregularity of flowers, and conspicuous among these forms are the sweet peas, irises and orchids. The story of cross-pollination in orchards has been told by Darwin in a wonderfully inteiesting book. The second division includes those flowers in which self-pollination is prevented, not by the relative positions of the parts, but by the fact that the pollen and stigma are not ready at the same time. When the stigma is ready to receive, the pollen may

not be ready for shedding; or when the pollen is ready for shedding, the stigma may not be ready to receive. These are the so-called dichogamous flowers (which see). It is evident that there may be two groups upon this basis : Those flowers in which the pollen is ready first and those flowers in which the stigma is ready first. The former are called protandrous the latter protogynous flowers. The third division includes those flowers in which there are at least two forms, and the two forms differ from one another in the relative lengths of their stamens and styles and in the nature of their pollen. For example, in the common houstoaia, a small tubular flower, one kind of flower has the stamens included in the tube and the stigmas protruding; while the other kind has the stigmas included in the tube and the stamens protruding. Each kind of pollen is most effective upon the stigma of the same level. Accordingly, as an insect passes from one such flower to another, crowding its way into the tube, its thorax is likely to receive a band of pollen from the short stamens and its abdomen another band from the long stamens. In this way the pollen from the thorax is rubbed upon the included stigmas and the pollen from the abdomen is rubbed upon the protruding stigmas. The whole story of the relation between insects and flowers is an exceedingly intricate one and full of surprises. John M. Coulter. Pollin'ium (in plants). In certain families, notably the milkweed and orchid families, all of the pollen-grains formed within a pollen-sac stick together in a mass which is removed bodily by insects. These masses of sticky pollen are pollinia.

Poll-Tax, a tax levied by the poll or head. In England the imposition of a graduated poll-tax in the time of Richard III led to Wat Tyler's rebellion in 1381. A similar tax was imposed in 1513. A tax, varying from i2d for a private person to 100 for a duke, was assessed in 1678 and abolished in 1689. In the United States some states impose a poll-tax varying from $1 to $3, while in others the imposition of such a tax is expressly forbidden by the state constitution.

Polit'ical Par'ties in the United States began as early as 1787, with the discussions as to framing the national constitution. When the delegates, chosen from the several states, had agreed unanimously upon a form, there was a difference of opinion as to its merits. Prominent among its friends were Washington, Hamilton, Jay and Madison. A series of 82 able papers in its favor, prepared almost wholly by Alexander Hamilton of New York, were published in The Federalist. At once those who sided with this view were called Federalists, and the opponents Anti-Federalists. When Wash-