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In the same year, WILM noted an increased mortality amongst mice in Hong- kong. In Sydney, ASHBURTON THOMPSON noted the presence of mouse plague.
In Alexandria, GOTSCHLICH found epidemic plague existent in areas more or less severely affected with the mouse epizootic.
My own experience leads me to believe, that during plague epidemics in. Hongkong, mouse plague is prevalent. Hundreds of mice have been examined bacteriologically and many found plague infected. My own researches up to the present time, however, do not warrant any definite conclusion in regard to the significance of the epizootic. My examinations have been only occasional. In the absence of a systematic investigation, one cannot definitely express an opi- nion as to the part played by these vermin in the furtherance of the disease. It would appear highly probable, however, that in many instances, mice play as important a part as rats, and that in dealing with epizootic plague, our sanitary efforts must be directed to mice as well as rats.
触
WILLIAM HUNTER.
The Susceptibility of Aminals in general to Plague Infection.
It would be out of the scope of a research like the present, to enter more or less fully into the question of the susceptibility of animals in general to plague.
In regard to many animals I have nothing to add to what is already generally known. The experiments carried out by Professor SIMPSON and myself, would appear to shed much light on this hitherto much discussed question. A report has already appeared in regard to these experiments,
The Guinea Pig-This animal shows practically the same degree of suscep- tibility to plague as the rat. It contracts the disease by all the wall recognised methods of natural and artificial induction. Acute and chronic plague are com- mon. Frequently a condition of Pest Marasmus is found in chronically infected animals.
It is the most suitable animal for experimental inoculation, and the isolation of the B. pestis from complicated micro-organismal nixtures. By cultural. methods, the isolation of plague bacilli from the faces, decomposing corpses of fluids, is practically an impossibility. In cultures the B. pestis is rapidly over- grown by ordinary non-pathogenic saprophytes.
It is known that saprophytic bacteria and ordinary intestinal micro-organisms, produce practically no pathological changes when rubbed into the shaved skin of a rat or a Guinea pig.
I have obtained excellent results with healthy rats. These results are in perfect accord with the observations of FRITSCHE (Årb. Kais. Ges-Aint. Bd. 18,. 1902) and MARTINI (Zeit. f. Hyg. Bd. 41, 1902).
The bacteria which may be present in such mixtures of micro-organisms. scarcely ever produce after careful cutaneous inoculation the characteristic patholo- gical changes of plague infection, namely, the extensive hæmorrhagic infiltration of the connective tissue, the bubonic swellings and the focal necroses in the spleen
An interesting pathological appearance is occasionally found, when plague bacilli of extremely low virulence are injected into the peritoneal cavities of Guinea pigs. Chronic plague is produced, and tumour like growths develop on the sur- face of the peritoneum, the liver, spleen and other organs. These are of the nature of granuloinata, and resemble tubercular or actinomycotic lesions. I have found a condition similar in the rat when suffering from chronic plague. Small nodules of soft granulomatous tissue were found in the peritoneal cavity, in the liver, and the spleen. Plague bacilli were present, but difficult of direct micros-- copic demonstration.