POLLINATION. 207 POLLIO. flowers are attractive to insects because of their fragrance, which is a device to secure cross-polli- nation. The pollen of insect-pollinated flowers is often comparatively sticky and heav}'. A lar"e niiniber of structures are found in these flowers which seem to favor certain insects and oppose others. Among the more striking of these devices it is winged ( Fig. 6. a ) . It is so abundant that it sometimes forms the so-called sulphur showers. (4) Water-pollinated flowers. A small number Fig 4. PEOTAXDRY. Flowers ot a flreweed, showinfr a young: condition (a) in which the stamens, but not the stigmas, are mature! anil an older condition (b). in which the pollen has gone,' while the stigmas are mature. Cross-pollination is thus effected. is a long corolla tube which favors insects with a long proboscis. In general, insect-pollinated flowers are rich in nectar, which is often the lure for the visit of insects. Other flowers are visited for their pollen, of which many insects are fond. (2) Bird pollination. A comparatively small and in North America unimportant number of flowers are pollinate'3 by birds, especially hum- ^/* Fig. 5. INSECT POLLINATION. • ^'•fflowe'" Of a legume, showing the normal condition (a) ana the condition which appears when an insect alights on ho J°,"'f 'i'- " '"^ obvious that insect pollination can oe readily effected here. ming-birds. (3) Wind pollination is common with a large number of plants, especially trees, grasses, and sedges, in which the flower's differ from insect-pollinated flowers in the relative absence of showiness, nectar, and odor, etc. these flowers are also comparatively small The poUcn is usually light, easily carried hv the wind, and is also produced in immense quanti- ties. Pine pollen is particularly interesting in that Fig. 6. POLLE.X GRAINS. (a). From the pine, showing bladder-like wings which facilitate dispersal, and (ft), from the hibiscus showing spmes which facUitat« attachment to the stigma. of aquatic plants are pollinated by means of water currents. In some cases, as in Vallisneria, a somewhat complex mechanism is present. POL'LIO, Gaius Asixius. A Roman orator, politician, soldier, and author of considerable merit. He was born in Rome B.c, 76, but be- longed to a family of ilarrusinian descent. When civil war broke out between Ca-sar and Ponipeius, Pollio sided with the former, was present at the crossing of the Rubicon, and took part in the battle of Pharsalia b.c. 48. At the time of Cipsar's assassination Pollio was governor of Further Spain, and cari-ying on the war against Sextus Pompeius. In the subsequent .struggles he sided with the triumvirate against the oli- garchic senate: and on the triumph of the for- mer, was appointed administrator of Gallia Transpadana, in which eapacitv he saved the property of the poet Vergil at Mantua from con- fiscation. After Antonius and Octavianus had quarreled, it was Pollio who effected their tem- porary reconciliation at Brundusium B.C. 40: next year he conducted a successful campaign against the Parthini, a people of Illvria, and in consequeuce obtained a triumph. ' After this event, however, he withdrew altogether from political life. He lived far into the reign of the Emperor Augustus, dying at his Tusculan villa A.D. 4, in the 80th year of his age. Besides having a reputation for oratorv. Pollio was cele- brated as an historian, poet, and critic. His liter- ary and political criticism of his contemporaries, in particular, appears to have been valuable. He also claims remembrance as a distinguished patron of Catullus?, Horace, Vergil, and other men of letters, and as the founder of the first public library at Rome. Of the writings of Pollio, we possess only three letters to Cicero ( published among Cicero's correspondence Xd FamUiares, v. 31-33). and a few fragments of his Histon/ of the Civil Wars collected by Peter, Historicorum Romanm-um Fragmenta (Leipzi", 1883). Wolfflin would attribute to Pollio the Bellitm Africaiuim (published with Ca-sar's works by Dinter, Leipzig. 1890). but this theory IS not generally accepted. Consult: Land<Taf,
