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THE BACILLUS.
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The Bacillus was found in practically every part of the body to which the blood has access. It was especially abundantly found in the enlarged glands and in the spleen. It was found in the other organs of the body and in the blood, but in fewer numbers. In the bubo and in the spleen they were found in much greater numbers in June than they were in September, and I have no doubt that they are always more numerous in cases where a large hæmorrhagic bub is present. Slight variation in size was met with. The bacillus taken from the blood looks. like a diplococcus, when stained with aniline dyes, the intermediate part only staining slightly. The bacillus taken from the bubo stains almost equally all over at first, but after keeping specimens for some time many of them show the appearance of those found in the blood, the staining of the interglobular part of the bacillus evidently not catching hold of that part so well. The bacilli vary slightly in size even in the same case. The capsule of the bacillus is usually distinct under the 1/12th oil immersion lens, and is best seen in some of the bacilli from a bubo where the interpolar part is not too deeply stained. The bacilli grow most abundantly on blood serum or glycerine agar agar at a temperature of from 96-100° F. The blood serum is not liquified. A culture from blool shows small grey semi-translucent colonies over the surface of the serum. Spore formation has not been noticed. When animals that are susceptible are inoculated with a cul- ture they get rapidly affected and die in a few days, the length of time varying generally according to their (the animals') size. Mice, rats, rabbits and guinea pigs are susceptible to the disease. The only pig that I inoculate is still alive, but as I have doubts as to the virulency of the culture a definitive opinion cannot yet be given as to the susceptibility of these animals Dogs have not yet been proved to be susceptible. The question of the infection of pigs is of the greatest importance, as so much of the meat supply of Hongkong consists of pigs brought from Pakhoi and Canton, where the disease may become endemic Strict measures may have to be taken in the case of a recrudescence of the disease in Canton. I can only say that so far as it has been noticed dogs seem to have escaped; dead dogs in the streets being conspicuous by their absence. Whenever a fresh culture of bacilli can be obtained this point will be cleared up.
After animals which had been inoculated died, the point of inoculation was found on dissection to present almost the same appearance as the peri-bubonic tissue in man. The spleen was generally enlarged, and in rats there was well marked enlargement of the lymphatic glands. Feeding animals on plague flesh and on buboes generally resulted in their death a few days after.
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A one per cent. solution of carbolic killed the bacilli after an hour's application. A two per cent. solution killed practically immediately. Quicklime was almost as efficacious. Four days' exposure of the bacilli to fresh air generally killed them--no positive results being obtained from culture after that exposure whilst bacilli exposed directly to the sun proved innocuous after four hours. (Temperature of Black bulb being from 150°-160° F.)
I have already mentioned that the bacillus may be found in the blood six weeks after the acute stage of the disease has passed; but this statement must be qualified by the remark that, in the later stages of the disease, it was found that they had generally disappeared in about three weeks.
Patients were not discharged from Kennedytown and Hygeia Hospitals until the bacilli had disappeared from the blood; but at the Chinese Hospital they were generally kept about two months, i.., those who recovered.
QUESTION OF QUARANTINE.
On this much debated subject it is perhaps best to say as little as possible. The question of quarantine, or the medical prevention of the introduction of disease must be decided by each country according to the sanitary state it is in; and upon the history of the disease as I have given it, and upon the facts there recorded the question will have to be settled. The great danger undoubtedly arises in most cases from its introduction by emigrants and their clothing from infected ports. Introduction by merchandise from an infected port though possible is very improbable indeed. If quarantine is to be imposed it is to be remembered that the incubation period has been proved to extend to nine days. I have no hesitation in saying that if immigration was disallowed in non-affected ports quarantine would be unnecessary; but if emigrants from an infected port are allowed to land then quarantine should be enforced, and more particularly so in the case of Chinese. Their baggage in