In some instances, the plague appears under the form of an inflammatory disorder, being accompanied with great heat, thirst, high-coloured urine, flushed cheeks, and violent delirium or phrensy; but in the greater number of cases it assumes the type of a nervous fever, being accompanied with little heat and thirst, and pale and turbid urine; the patients think themselves only slightly indisposed, until a sudden prostration of strength, and the eruption of buboes, carbuncles, petechiæ or vibices, announce to themselves, as well as to those who are about them, the danger they are in. In some few instances, the plague appears under the form of an intermittent fever.--Almost all those who are carried off by this disorder, die before the sixth day; those who get over the seventh day have a good chance of recovery[39]. The diversity of symptoms above-noticed, has given rise to the opinion that there are three different species of the plague, viz. one which is accompanied with petechiæ, another with carbuncles, and a third with buboes; but the history which we have given, clearly proves, that these are only shades or modifications of one and the same disorder, which is more or less violent under different circumstances and at different seasons. Petechiæ, buboes, and carbuncles often appear at the same time in the same patient, or occur in succession. In the month of July, great numbers of the impested died before the tumours came out, having petechiæ only; whereas in August and September, almost every patient had petechiæ, joined with buboes and carbuncles. After the middle of October, when the contagion was less virulent, although it still produced petechiæ and carbuncles, yet they were neither so malignant nor so frequent. Before this period, scarcely four patients in a hundred recovered; whereas during the latter months of the year, the proportion of recoveries was much greater. _Sydenham_ has made the same observation respecting the plague at London[40]. Nature endeavours to throw off the poison by buboes. Carbuncles and petechiæ are not critical eruptions; they only denote a putrid condition of the humours, and a great degree of acrimony; whence it follows, that in proportion as buboes are more common, and petechiæ and carbuncles more rare, the milder the plague is[41]. * * * * * To this account which Dr. _Mertens_ has given of the symptoms which the plague at Moscow exhibited, we shall add the descriptions drawn up by two other practitioners (_Orræus_ and _Samoïlowitz_,) who had great opportunities of observation, and who have been more particular in noticing some of the phenomena than our author. According to _Orræus_ (Descriptio Pestis, &c.) the plague in Russia appeared under four different forms or varieties. Of these, he terms the first, _the period of infection_; the second, _the slow type_; the third, _the acute type_; and the fourth, _the exceedingly acute type_.