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most stress on the fact that the heavy rains drove coolies and others into the infected houses to sleep instead of sleeping in the street as they generally do in the summer when the weather is at all good.
MODE OF INFECTION.
The poison is given off in the fæces, in the blood and in the contents of buboes. Skin to skin infection is impossible unless the one to be infected has some wound and the infector's skin has been soiled by fæces, blood or the contents of buboes. The poison is not given off in ordinary respiration. Cultivation experiments with, and microscopic examination of, sputum and saliva have given negative results in the only case in which I have been able to work on this point. The question of whether the bacillus is present in the vomit has not yet been solved. Dr. KITASATO does not at present think so, but seeing that animals feeding on bits of plague buboes contract the disease, I think it better to give a guarded opinion upon this point. That the bacillus may live under certain conditions in the stomach is evident; what these conditions are I cannot state, but in an unhealthy stomach with great decrease of gastric juice it is quite possible for the bacilli to live and even multiply.
Infection takes place by inoculation, inspiration, and introduction into the stomach. The latter is infrequent. In this epidemic the relative frequency of the two first mentioned channels could not be made out, and indeed it would be diffi- cult at any time to determine, as in cases of inspiratory infection the primary bubo noticeable may be situated in any part of the body, whilst a scratch on the hand or foot which may be thought the primary wound is often an after result of an injury unimportant at incipience. Most of the coolies affected wore neither shoes nor stockings; almost all inales go barefooted which would partly account for the large number of the coolie class being affected. The better class of Chinese, though living under almost identical sanitary conditions, generally wear shoes and stockings. Infection from bodies found in street or houses or awaiting burial may take place if clothes, etc. have been soiled by discharges.
Infection by flies and mosquitoes is improbable as no attendant in Hospital, although frequently bitten by these insects was affected. No bacteriological ex- amination of mosquitoes or flies was made.
INCUBATION.
The incubation period may extend to nine days; it is, however, generally from three to six days. How short it may be I do not know, but I should say that a few hours' incubation period is very improbable, Case I. had an incubation period of between one hundred and two and one hundred and thirty-eight hours. The first batch of soldiers who were affected were seized with fever three-and-a-half. four, and six-and-a-half days respectively (after cleaning out some badly infected houses), while another soldier had an incubation period of four days. Of course these dates may be wrong as far as incubation is concerned, as they might have been infected at any time during these days but at any rate the evidence is signi- ficant. The limit period was in the following case. A Chinaman, MAN CHOY, was arrested on June 11th and put in the Police Cells during the day. He was sent. enced to imprisonment in Gaol on 12th June, and on 20th June in the evening, after having complained of not being well and being under observation for two days, became feverish, and was removed to Hospital. The following day (21st) a left femoro-inguinal bubo appeared. This case gives an incubation period of nine days and is very important. There were many cases where an incubation of be- tween three and six days could be proved, at least so far as one can speak of proof when eliciting evidence from Chinese. The Eurasian Italian Convent Sister who died from plague had an incubation period of five days.
The matter may be summed up as follows, the incubation period is generally from three to six days, is seldom under three or over six, but may reach nine.
CLINICAL.
Before describing in detail the clinical aspects of the bubonic plague it may not be out of place to give a brief description of the condition in which we found the sufferers during the early weeks of the epidemic. In those days, very naturally, cases were discovered in a more advanced stage of the malady than later, when house-to-house visitation was well established, and hidden sufferers were less frequently found. To overpaint the pitiable surroundings associated with plague work at the cominencement of the epidemic would be impossible.
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