It is difficult to differentiate a case of true plague in its early stages from a case of fever with benign glandular swellings or mumps. The premonitory symptoms of plague, and even the early symptoms of the first stage, may be due to many different diseases and therefore great caution is needed. It is needless to say how important it is that such diagnosis should be done with great care, specially when plague cases have to be isolated, for if a case of simple fever with benign lymphadenitis be brought in close contact with patients suffering from true plague, it is a serious matter with the former. A venereal bubo, or scrofulous enlargement of glands, or enlargement of femoral or inguinal gland due to traumatic or other causes which may be attended with fever should not be mistaken for a plague symptom. A medical man who has, however, carefully observed the facies of a few cases of true plague, and who carefully takes into consideration all other probable conditions which may be mistaken for plague, may not commit a mistake, but its probabilities are to be borne in mind. The practical lesson is, that all doubtful cases should be isolated and kept separate from cases of pronounced type. The plague bears some resemblance to typhus. Murchison says: “Plague is perhaps the typhus of warm climates, the two diseases being generated from similar causes and differing only in intensity from the effects of climate and other collateral circumstances.” In typhus there is a characteristic rush, and in plague there is bubo, but this order of things have been found in some instances to have changed, there being eruption in plague and bubo in typhus. The two diseases are, however, different and bacteriological and clinical evidence corroborate this view. Cantlie adds another disease, which he says he mistook for plague:—“On June 26th, 1894, when the plague was at its height, I saw a Parsee patient dwelling in a house in which plague existed, suffering from fever 104°(F.), dry tongue, headache, backache and large swollen glands in the left groin, which had suddenly appeared. Plague seemed the only diagnosis, and the man, much against his will, was sent to the plague hospital. In two days he came back again quite well, and on examining him I found his urine thick and milky. That night I found filaria in the man’s blood, and knew I had made a mistake in the first instance. Of course, the mistake is most likely to happen, but nevertheless it is not pleasant to think that we had subjected the man to the terrible danger of plague infection.” _PROGNOSIS._