PBUNING. 487 PRUSSIA. have no intimate connection with the soil by which the deiiuinds of the expanding leaves can he supplied with food and moisture; in fact, the demands of the top should be less than the root ( .in meet in order that a too severe strain shall nut be placed upon the organism. Pruning may be performed for the purpose of correcting the liabit of growth. The head may be made high Hi- low, compact or open, at will, almost regard- less of the natural habits of the tree. In gen- I eral, however, the peculiar nature of the tree should be taken into account and the pruning made to conform as closely as possible to that lorm. here fruit is the object sought the man- ner of fruit production of the plant must be thor- oughly understood, otherwise pruning may in- duce wood growth at the expense of fruit pro- duction. For instance, apples and pears bear fruits upon spurs; peaches, usually on the young iiranches (sometimes on spui-s) of the previous xason's wood ; grapes, on wood of the current year produced from buds dcvelo|jed the year previous. In order, therefore, intelligently to prune any plant for fruit production, its fruiting habit must be carefully considered. Sometimes desired results are obtained by root pruning, or liy cutting away a portion of the bearing wood. In the first case fruit-bearing is induced, in the second the fruits are thinned or their number decreased, the food supph' distributed to a less- ened number which may be corres|)ondingly in- creased in size. Pruning also admits light to the tree tops b_v removing supcrlluous branches, thus making the fruits higher colored. Besides these ol)jects pruning is used to change the form of head ("heading in'). Whatever be I he object, the operation should be performed in the manner least injurious to the jilant. This in- volves the method of removing the branch and the . time of year the work should be done. In regard to the season for pruning little e.xact information can be given. As a rule apples, jiears, and cher- ries suffer least if pruned wliile in full vigor of •growth. The wounds heal readily and there is I'-s liability to loss of vitality than at other sea- "iis. The peach should be pruned early and verely for wood growth, and late and lightly lor fruit production ; the same is also true of the grape. All pruning of the grape and peach should be conlined to the resting period. The manner of pruning so as not to lessen the vigor or shorten the life of the plant involves systematic annual pruning, by which the removal of large branches can be avoided. .All cuts should he made close to and parallel with the main luanch so as to promote the healing process. Large wounds must be coered with some preser- vative or protective coating to prevent decay. The healing of a wound is accomplished by the formation of a callous from the growing tissues. The process continues, and liy the annual deposi- tion of new material the wound is covered. A smooth cut will heal where a jagged cut or bruise will decay. Trees grown upon walls or espaliers require great skill in pruning in order to hold them within bounds, and at the same time secure the maxiiiium production of fruit or flowers. In grape-growing certain styles of pruning have been siiven special names — c.g, re- newal, high renewal, Kniffen. etc. Ornamental trees are either pruned for the purpose of correcting the habit of growth, as the shortening of a leader in order to thicken the growth and make the tree broader, or for the purpose of giving the plant a particular form, as is the case with hedge plants and with ever- greens u.scd in formal gardens. Consult Bailey, The Pruning Book (New York, 1898), also numerous experiment station bulletins. PRUKI'GO (Lat., itch). The name of a skin disease restricted to prurujo of Hebra, not in- cluding all conditions in which there is pruritis. Fornierly dermatologists distinguished prurigo mitis, prurigo formicans, and prurigo senilis, Avhich are now relegated to the eczemata and the lichens (q.v.). True prurigo, also called pru- rigo agria or ferox, begins in infancy or in child- hood or youth, persisting with recurrences for many years. It resembles Mrd'carm (q.v.). The eruption is generally at first a series of white or rosy plaques with itching, agitation, and insomnia. Then papules appear, as pale red points, ex- coriated at the summit, usually on the anterior and external portions of the "legs and thighs, about the pelvis and buttocks, and also upon the upper extremities. The skin hardens, and be- conies thicker, furrowed with folds and covered with crusts. Vesicles may appear, exuding yel- lowish serum, or sanguineous, and blackened. Impetigo, furuncle, abscess, and lymphangitis, all resulting from inoculation, may complicate the attack. Indolent lymphatic glandular enlarge- ments may appear in the groin. The prognosis is very unfavorable. The disease generally dis- appears between the eighth and eighteenth year, in the milder eases. ^lany are incurable. Asth- ma, emphysema, and chronic bronchitis are very common anionir the victims of prurigo. Diet, enil-liver oil. pilocarpine, carbolic acid, cannabis indica. and analgesics are of avail. Bran baths, starch baths, eod-Iiver oil, styrax, sulphur, ichthyol, and resorein are among the local appli- cations used. Hermetically sealing up the skin is the most eflrectual treatment of all. Consult Kaposi. Pathology and Treatment of Diseases of the ■Sffcin (Eng. trans., New York, 1895). PRUSSIA, prush'A. A kingdom and the larg- est State of the German Empire. By the Im- perial Constitution of 1871 the King of Prussia bears the title of German Emperor. The Prus- sian territoi-y completely or nearly surrounds that of five of the smaller States of the Empire — the giand duchies of ^lecklenburg-Scliwerin and Mecklenburg-Strelitz, the duchies of . - halt and Brunswick, and the Grand Duchy of Oldenburg; also the three free towns of Liibeck. Hamburg, and Bremen. With these ex- ceptions the whole of Xorth Germany and its low- plain are embraced in the Kingdom of Prussia. A small detached portion of Prussia, Hohenzol- lern, is in the extreme south of the Empire. Exclusive of Hohenzollern, Prussia extends from latitude 49° T to 55° 54' I., and from longitude 5° 52' to 22° 54' E. It is bounded on the north by the North and Baltic seas and Denmark, on the east by Russia (mainly Poland), on the south by Austria-Hungary. Saxony, the Thurin- gian States, and the South German States, and on the west by the North Sea, the Netherlands, Belgium, and Luxemburg. With an area of 134.- 548 square miles, it embraces more than three- fifths of the territory of the German Empire. It also has three-fifths of the population of Ger-
