onist of the encroachments made in name of the royal prerogative. He was one of the founders of the Fortschrittspartei (Progressists), and both as such and as a subsequent member of the deutsch-freisinnige party he was one of the most prominent figures of the German Reichstag from 1880 to 1893.

The first edition of his master-work, Cellularpathologie, was published in 1858, and attracted at once the attention and admiration, and later won the acceptance of the medical world, displacing the former pathological systems and theories for all time. (See PATHOLOGY.) His views were so clear, his theory so perfect, and his grasp of the matter so comprehensive that his fame was at once assured. His work upon tumors is of especial value, as it holds the prac tical and clinical aspects of the matter as of prime importance-a circumstance that is remarkable in view of the fact that Virchow was not a practitioner of medicine. His views combated the pessimistic theories of Rokitansky and the prevailing Vienna school of pathologists. His work in pathology is distinctly a creation, establishing the biologic principle that the laws working in disease are not different from those in operation in health, though subject to different conditions. The cellular theory was finally established in 1858. During the wars of 1866 and 1870-71, Virchow devoted himself to arranging, equipping and drilling hospital corps and ambulance squads, and directed the management of numbers of hospital trains, also taking charge of the immense Berlin military hospital, as well as of the sanitary arrangements of the troops in the field. The Franco-Prussian War ended, Virchow became a member of the Sanitary Bureau of the city of Berlin, with its problem of the disposal of sewage, neither of the two little streams near it being capable of receiving and transporting the refuse. Under his direction immense sewage farms were established after such a plan that they have kept pace in adequateness with the tremendous growth of the city, while the revenue from them is sufficient to meet and defray the expense of their mainte

On October 13, 1901, upon the celebration of his eightieth anniversary, at a complimentary dinner in Berlin, a Festschrift was presented to him by a score of former students. Simultaneously testimonial dinners were given in other cities, notably New York and Chicago, in the United States, at which many physicians vied with each other in recounting the discoveries and sounding their praises of the great scientist, teacher, physician, and legislator.

Perhaps Virchow's greatest material monument is the Pathological Institute and Museum in Berlin, erected by the Government in accordance with his desires. It contained 23,000 specimens at the time of his death, and by far surpasses all similar collections in the world.

He was a very voluminous writer. Among his works are Mittheilungen über die Typhus

Epidemie (Berlin, 1848); Die Cellularpathologie (ib., 1858; trans., London, 1860); Handbuch der speciellen Pathologie und Therapie (ib., 185462); Vorlesungen über Pathologie (ib., 1862-72); Die krankhaften Geschwülste (ib., 1863-67). He also published many works on various topics, such as the gorilla, plague in its relations to public health, Goethe, Johannes Müller, spedalska (a disease peculiar to the Norwegian coasts), etc. Consult his Life by Beecher (Berlin, 1891).

VIREO (Lat. vireo, greenfinch, from virere, to be green, vigorous), or GREENLET. The common birds, having a plumage more or less tinted with name of a family of about fifty insectivorous short, straight, notched, and hooked at the tip; green and olive. In the genus Vireo the bill is wings long and pointed; toes of moderate length; tail moderate and even. There are about 30 species, a dozen of which occur in the United States, most of them migrating to and from these birds are singers, and the variety of song South America and the West Indies. Many of in the genus is great. All subsist exclusively upon insects, and are of immense service to the gardener and orchardist. All agree, also, in constructing a very artistic nest in the form of a cup of ribbon-like materials, such as grape-vine bark, ornamented with cobwebs, lichens, and the like; the typical form is shown on the Plate of PENSILE NESTS OF BIRDS, under NIDIFICATION.

The most familiar and widespread species in the United States is the red-eyed vireo (Vireo olivaceus), about six inches long; back and tail bright olive green, crown ashy, and a characteristic double line, dusky and white, over the eye, the iris of which is red. The white-eyed vireo (Viero Noveboracensis) is very similar, but has barbatulus, called 'Whip-Tom Kelley' in Jamaica a white iris. A more southerly species is Vireo after its call-notes. Of the others, the most striking is the yellow-throated (Viero flavifrons), which is bright olive green above, pure white beneath, and with the throat and breast bright yellow.

VIRGIL. See VERGIL.

VIRGIL'IA (Neo-Lat., named in honor of the Latin poet Virgilius, Vergilius, Vergil, in allusion to his agricultural poem, the Georgica). A genus of leguminous trees, natives of South Africa. The only species, Virgilia capensis, is a handsome tree 15-20 feet tall occurring abundantly along streams in Cape Colony. The wood is light, soft, and easily worked, and is much used for yokes, spars, etc. To this genus Michaux referred a North American tree, the yellowwood (Virgilia lutea), but, from differences in the pods and other parts, Rafinesque made a new genus for it, Cladrastis, which is its present botanical name. See CLADRASTIS.

of the estuaries navigation is blocked on all the rivers at the Fall Line, where the streams fall over the escarpment of the Piedmont Plain. The only lake in Virginia is Drummond Lake, situated in the centre of the Dismal Swamp (q.v.), in the southeastern corner of the State.

CLIMATE. East of the Blue Ridge the climate is mild or temperately warm, with a mean temperature of 37° for January and 77° for July. The minimum here rarely falls below 10°, while the maximum may reach 110°, though it is generally about 100°. In the uplands the climate is dry and healthful, but malarial diseases are endemic in the tidewater section. West of the Blue Ridge the summers are cool and very pleasant, while the winters, especially on the mountains, are cold. The mean temperature at Staunton, in the Great Valley, is 33.4° for January and 74.6° for July. The minimum in this section may reach 8° below zero. The rainfall is sufficient throughout the State, and favorably distributed for agriculture. It is greatest in the central portion near Richmond, where the average is 48 inches. In the Great Valley it is 38 inches.

SOIL AND VEGETATION. The soils of eastern Virginia are in general light and sandy, except in the bottom lands and in the marsh regions, where a deep layer of vegetable mold has accumulated. In the Piedmont upland the soil is generally more fertile, having been enriched by decayed greenstone material. The most fertile portion of the State, however, is the Great Valley, where the underlying rocks are ancient limestones, whose decomposed materials are admirably adapted for wheat and other grain. The forests are still of considerable extent, and consist in the coastal plain chiefly of yellow pine and cedar, with cypress in the swamps and some oak, hickory, locust, and persimmon. In the western uplands there are large forests of deciduous trees, with white pine on the mountains, and with the general characters of the Appalachian floral region. See paragraph Flora under UNITED STATES.

GEOLOGY AND MINERAL RESOURCES. As in the other Atlantic States, the principal geological formations run in parallel bands from southwest to northeast, and correspond closely to the topographical regions, whose characteristics, in fact, are dependent upon the underlying rock formations. The coastal plain or tidewater section is overlaid by unconsolidated strata of sand, gravel, clay, and marl of Tertiary and later origin. The western boundary of the coastal plain formation runs from the neighborhood of Washington due south, passing west of Richmond. Between this line and the Blue Ridge the country is of Archæan origin, consisting of granite, gneiss, syenites, and slates, with intrusions of greenstone in the west. The central part of the region, however, was submerged in early Mesozoic times, and several large patches of rock belong ing to the Jura-Trias system still remain. The Blue Ridge consists mainly of Potsdam sandstone of the Cambrian system, and the valleys and ridges to the west of it are of Lower Paleozoic age, Silurian limestone predominating in the valleys, and Devonian rocks on the ridges. A peculiar feature of the limestone region in the Great Valley is the formation of great caverns which rank among the foremost natural

curiosities in the country, such as Weyer's Cave in Augusta County, and the arched remnant of a cave, famous as the 'Natural Bridge,' in Rockbridge County.

Virginia has a great and varied mineral wealth. Iron is found as magnetite along the eastern base of the Blue Ridge, limonite on its western slope and in various other localities, and red hematite in the western Alleghanies. Other metals found in the mountain region are zinc, lead, tin, and copper, and manganese is widely distributed. Through the Archæan rocks of middle Virginia runs an auriferous quartz reef, and silver is also found in small quantities. Building stones, granite, limestones, and sandstones are found of great beauty and variety, and in inexhaustible quantities. Hydraulic limestone is also abundant, and in the southwestern corner of the State there are immense ledges of gypsum and rock salt. Even the tidewater section contains valuable minerals in the form of greensand marl.

Coal

MINING. The mining industry has never reached any great development, but it has, nevertheless, for a long time been an important factor in the industrial history of the State. (mostly bituminous) is mined in the Appalachian region. The total product of the State, as reported for the year 1882, was 112,000 tons, and increased to over a million tons for 1888. There was then a steady decrease of product until 1892, when it fell to 675,205 tons. Subsequently, however, extensive developments in Wise County brought up the annual output again to more than 1,000,000 tons. Some of this product is used in the making of coke. The output of iron rose in 1900 to 490,000 short tons. Almost all of this was brown hematite, constituting one-half of the country's output of that ore. Considerable quantities of stone, principally granite, limestone, and slate, are quarried in the central and Piedmont districts. The annual value for the last decade approximated $500,000; in 1900 it was $670,000. Virginia is one of the important mineral-water States; the product of 39 springs aggregated $320,000 in value in 1899. Gold, silver, and some other minerals have been mined for a long time, but are at present of very little importance.

FISHERIES. Virginia ranks close to Massachusetts, New York, New Jersey, and Maryland in the importance of sea fisheries. In 1897 there were 28,000 men employed in the industry, this being a decided increase over the beginning of the decade. There was also an increase in the total product, but the value ($3,179,000) was much less, owing to the decline in prices. About two-thirds of the total product represented oysters, and it was in these that the decrease in price was greatest. Among other varieties, shad, menhaden, clams, and alewives are most important, the first three showing an increase in value during the period 1890-1900.

AGRICULTURE. The short mild winters and the long summers, with plentiful rains, are conducive to farming. The soil, however, is generally much inferior to the soils of the Mississippi Valley, and the yield per acre very much less. There is a great variation of soil in the different physical divisions. The region of greatest fertility is the Shenandoah Valley, while the Piedmont district, extending across the State in a southwesterly direction par