734 Y E D Y E L in beer-brewing is available ; but its bitter taste is an objec tion to it. Hence it has long been customary in Germany to produce yeast expressly for bakers and cooks purposes, which may, of course, be done in a variety of ways. A method frequently used is to produce a wort (see BREWING, vol. iv. p. 275) from barley, malt, and rye, and by the addi tion of a little ready-made yeast to let it ferment under con ditions which favour the growth of yeast-cells, but restrict the proportion of alcohol produced to a minimum (comp. FERMENTATION, vol. ix. p. 97). During the most tumultu ous period of the process the yeast is skimmed off from the surface, washed with water, and either " filter-pressed " or " centrifuged " to obtain it as a relatively dry paste ; it is then mixed with a proportion of dry starch, to give it a higher degree of dryness. Such yeast goes into commerce as presshefe or pfundhefe (German yeast or barm). This industry used to be a monopoly of Germany ; but quite lately the manufacture of German yeast has been taken up in Scotland. YEDO. See TOKIO. YEISK, a district town of the Russian province of Kuban (Caucasus), was founded in 1848 at the mouth of the Yeia, on a narrow sandbank which separates the shallow Bay of Yeisk from the Sea of Azoff, 108 miles to the south-west of Rostoff-on-the-Don. Notwithstand ing its shallow roadstead, which has a depth of 14 feet only at 2 miles from the shore, Yeisk has grown with great rapidity, and in 1884 had 23,725 inhabitants. Corn, linseed, and wool are exported to a considerable extent (1,730,000 cwts. of corn and flax and 10,000 cwts. of wool in 1885), and the port was visited in 1886 by 69 ships (30,000 tons) engaged in foreign trade and by 697 (80,800 tons) engaged in the coasting trade. There are large wool- cleansing factories, oil-works, and tanneries. YEKATERINBURG. For this and similar forms of Russian town-names, see EKATERINBURG, &c. YELETS, a district town of the Russian government of Orel, 121 miles by rail to the east of Orel, stands on the great trunk railway which connects Riga with Tsaritsyn on the lower Volga ; a branch line connects it also with the railway which runs from Tula to Samara and Orenburg. Owing to its advantageous position Yelets, which had been for a long time an important entrepot for the corn trade, has rapidly grown of late, and in 1883 had 36,680 inhabit ants. The Yelets merchants buy large quantities of grain in the fertile neighbouring provinces, and send their agents to southern and south-eastern Russia ; nearly 1 50 flour-mills, many of them driven by steam, prepare flour, which is forwarded chiefly to Moscow and partly to Riga. The trade in cattle is also very important. Yelets has become of late a manufacturing centre, and has some im portant tanneries, foundries for cast-iron and copper, tallow- melting Avorks, sieve manufactories, &c. The town has several educational institutions. Its cathedral and two monasteries contain venerated historic relics. Yelets is first mentioned in 1147, when it was a fort of Ryazan. The Polovtsys attacked it in the 12th century, and the Mongols destroyed it during their first invasion. The Tartars plundered it in 1415 and 1450 ; and it seems to have been completely abandoned in the latter half of the 15th century. Its development dates from the second half of the 17th century, when it became a centre for the trade with south Russia. YELIZAVETGRAD. See ELIZABETHGRAD. YELIZAVETPOL. See ELIZABETHPOL. Type and YELLOW FEVER is a typhus-like fever of certain circum- ports, or of ships hailing from them. It differs from all other existing types of fevers and infections in largely sparing the Negro. It resembles cholera in being en demic in some parts of the world (but only shipping places) and in being importable to others, in being an infection that issues from the soil or some medium equi- stances. valent thereto, and in being a virulent filth-disease ; but it differs from cholera in having at the outset a violent febrile paroxysm lasting two or three days. As a fever it resembles typhus ; but it differs from typhus in all those " exogenous " characters wherein it resembles cholera. The generic place and affinities of yellow fever are perhaps best provided for in the nosology of Cullen : the symptoms are within the sphere of the organic nervous system ; they stand for excitement first and prostration afterwards ; and they are an effect of human effluvia. Its differentia among the " nervous " fevers due to " human effluvia " would be its maritime or amphibious habitat, its associa tion with tropical heat, the chief part played by the liver in its symptomatology (on the lines of acute yellow atrophy), and the singular immunity of the Negro race. An attack of yellow fever may follow definite exposure Char (such as landing at an endemic port) within a few hours, teris as in corresponding cases of cholera ; but the outbreak of symptoms is more often delayed for a few days, the limit of " incubation " being about eight. The few hours languor, chilliness, headache, and muscular pains, which might be the precursors of any febrile attack, are followed by a peculiar look of the eyes and face, which is charac teristic : the face is flushed, and the eyes suffused at first and then congested or ferrety, the nostrils and lips red, and the tongue scarlet, these being the most obvious signs of universal congestion of the skin, mucous mem branes, and organs. Meanwhile the temperature has risen to fever heat, and may reach a very high figure (maximum of 110 Fahr., it is said); the pulse is quick, strong, and full, but may not keep up in these characters with the high temperature throughout. There are all the usual accompaniments of high fever, including hot skin, failure of appetite, thirst, nausea, restlessness, and delirium (which may or may not be violent) ; albumen will nearly always be found in the urine. The fever is a continued one so long as it lasts ; but the febrile excitement comes to an end after two or three days. In a certain class of ambulatory or masked cases the febrile reaction may never come out, and the shock of the infection after a brief interval may lead unexpectedly and directly to prostration and death. The cessation of the paroxysm makes the stadium, or lull, characteristic of yellow fever. The hitherto militant or violent symptoms cease, and prostration or collapse ensues. The internal heat falls below the normal ; the action of the heart (pulse) becomes slow and feeble, the skin cold and of a lemon-yellow tint, the act of vomiting effortless, like that of an infant, the first vomit being clear fluid, but afterwards black from an admixture of blood. It is at this period that the prospect of recovery or of a fatal issue declares itself. The prostration following the paroxysm of fever may be no more than the weakness of commencing recovery, with copious flow of urine, which even then is very dark-coloured from the presence of blood. The prostration will be all the more profound according to the height reached by the temperature during the acute paroxysm. Much blood in the vomit and in the stools, together with all other hsemorrhagic signs, is of evil omen. Constant hiccough, with loud cries or wailing, is a certain sign of death, which may also be ushered in by suppression of urine, coma, and convulsions, or by fainting from failure at the heart. The proportion of recoveries is usually less than one-half ; but it has been now and then very large (as in the New Orleans epidemic of 1878). Convalescence is on the whole rapid ; but, if some old disease, such as ague, have been lighted up, or abscesses induced, it may go on slowly for months. One attack of yellow fever confers a high degree of immunity from a second. The treatment of yellow fever has been one of the classical sub- Treat-
jects of controversy. In the Philadelphia epidemics of the end of meut.