Island. On December 10, the fourth day of the eruption, a few vesicles appeared for the first time. These formed slowly about the lower part of the abdomen and thighs. At these sites were four or five typical umbilications. On December 11, the fifth day of the eruption, many more umbilications were found. The patient became rapidly worse, and died on the following day, December 12.

Case II.—Mr. F. S., aged twenty-four years. Removed to Reception Hospital on suspicion of typhus fever. On December 8 the appearance of this case was similar to Case I., inasmuch as the face was swollen and presented an erysipelatous appearance, although the color was more of a dusky hue. Large erythematous patches, suggestive of scarlet fever, were found covering different parts of the body. The same condition was present in this case as was noticed in Case I.,—i.e., the color of the patches was darker than in scarlet fever, and when the finger was drawn over the patch it did not leave a white line. No patches were found on the arms; but at these sites were dark, almost black, papules, which slowly became vesicular and umbilicated. The eruption was confluent on the upper part of the thighs and the face, and the patient died on December 8.

Case III.—Mr. P. B., aged twenty-six years. Removed to Reception Hospital, December 16, 1893, on suspicion of typhus fever. On December 17 he presented the following appearance: The face and the entire trunk and upper portions of the thighs and shoulders presented an eruption which could easily have been mistaken for scarlet fever. The eruption was dotted with dark or black papules; some vesicles were noticed on the trunk. The eruption on the thighs was shotty and umbilicated and quite characteristic of variola. The face presented the same appearance as in Cases I. and II. On the legs and forearms, where the general redness was not present, the eruption had hardly gone beyond the macular stage, but was very dark,—almost black. As in the other cases, the finger drawn across left no white mark. It was stated that epistaxis had occurred. The patient became rapidly worse, without much change in the eruption, and died on December 17.

Case IV.—Mr. L. R., lawyer, aged forty-three years. Removed from boarding-house, December 24, 1893, to Reception Hospital. Seen at home previous to removal, December 24. Patient felt badly on December 17. On December 20 was quite ill; pains in different parts of the body; nausea and vomiting. This condition continued until December 23, when an eruption appeared. Diagnosis, scarlet fever. On December 24, with the exception of the legs and forearms, the entire body and face was involved in a general eruption resembling scarlet fever. However, as in the preceding cases, it was of a darker hue than that found in scarlet fever, and pressure upon the skin made no impression so far as changing its color. Over the legs and forearm was distributed a profuse papular eruption, very dark in color. On other parts of the body were scattered some dark or almost black papules, with a few vesicles; typical umbilication was also present in some. A few small vesicles were noticed on the nose. These had the appearance of inflamed follicles, and were not as dark colored as the rest. The conjunctivæ were very much congested, and the membrane of the mouth was so much swollen that it was impossible to examine the throat. Hematemesis was present, also great prostration from the outset. The patient died on December 25.

CHAPTER II.

DIAGNOSIS.

There are few diseases the prompt recognition of which is of greater importance to the physician than variola. On the one hand, failure to recognize the disease may subject the family of the patient and the community at large to the danger of contagion, and thus even be the starting-point of a widespread epidemic; on the other hand, to pronounce a case smallpox when it is not, entails so much needless pain and anxiety that the physician guilty of so grave an error merits the severe condemnation which will certainly be visited upon him.

The recognition of a case of smallpox may be simple, difficult, or even impossible, depending on the case and on the stage of the disease. In general the disease is readily recognized when the case is typical and the eruption has reached the vesicular or pustular stage. The diagnosis is difficult in atypical and complicated cases. It is impossible with any degree of positiveness in most cases in the pre-eruption period,—the stage of invasion.

The initial symptoms of smallpox resemble the first symptoms of so many infectious fevers that it is only through a consideration of the prevalence of an epidemic and the opportunities for infection in a given case that the physician may be put on his guard. It is important in this connection to notice whether the patient has been successfully vaccinated within a recent period. The physician who during the prevalence of an epidemic finds an unvaccinated subject suffering from a febrile disease of acute onset, with severe lumbar and dorsal pains, may, in the absence of definite symptoms pointing to some other disease, suspect smallpox; but a positive diagnosis at this stage is, of course, impossible.

Prodromal Rashes.—The occurrence of the prodromal rashes, the roseola variolosa,—a more or less diffuse scarlatiniform, morbillic, or urticarial rash which may appear on the second day of the fever,—has a certain diagnostic value; but this roseola occurs in only a small percentage of the cases, and, unfortunately, sometimes appears in other acute toxæmic conditions,—typhoid, for instance. The scarlatiniform rash may lead to a diagnosis of scarlet fever and the morbillic roseola be mistaken for measles; but these diseases would be excluded by the absence of the angina and the strawberry tongue of scarlatina in the one case and of the catarrhal symptoms of measles in the other, aside from other considerations. The appearance of the eruption on the second day of scarlatina is followed by a marked defervescence, while the scarlet rash of smallpox is not accompanied by any change in the temperature curve. The eruption in measles occurs on the fourth day of the illness, a circumstance which alone suffices to differentiate it from the morbilliform roseola of smallpox. The characteristic and pathognomonic “Koplik spots” on the buccal mucous membrane in measles are, of course, absent in smallpox. Furthermore, these prodromal eruptions of variola are of extremely evanescent character and usually disappear within eight or ten hours.

Of somewhat greater diagnostic value in this stage is the appearance of small hemorrhages, or petechiæ, varying in size from a pin’s head to a pea, in the brachial and crural triangles of Simon. This form of prodromal eruption, however, is extremely rare, and, it may be added, is of grave prognostic significance, as it is usually the precursor of hemorrhagic smallpox.

Meningitis.—The intense headache, vertigo, delirium, and coma of meningitis, especially meningitis of the convexity without localizing symptoms, may be mistaken for severe prodromal symptoms of smallpox. As a rule, pulse and respiration are slow in meningitis, while in smallpox respiration and pulse are both markedly rapid.

Cerebro-spinal Meningitis.—In cerebro-spinal meningitis, in which an erythematous or purpuric rash appears, the difficulties of diagnosis are often such as tax the skill of the most expert clinician. It is important to remember that the rash of cerebro-spinal meningitis usually develops gradually or in successive crops, and that its distribution over the cutaneous surface is irregular, while the eruption of smallpox makes its complete appearance within the space of a few hours and is