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494 is only the presence of an epidemic of dysentery at the time, or the post-mortem revelations, that make diagnosis possible. The mortality in such cases is very high. Occasionally the acute phase subsides, the patient slowly recovering after passing through the ulcerative phase of the disease. Relapsing dysentery.— In a proportion of dysenteries, although the activity of the initial attack may subside somewhat, symptoms do not completely disappear. The stools may recover their fæculent character and even show some formation, but they continue to be passed too frequently, are often preceded by griping, and contain a variable amount of slime and muco-pus, with or without blood. Without obvious cause, or as a sequel of some dietetic or other indiscretion, these dysenteric signs become aggravated, and there is once more a recurrence of active symptoms. Spontaneously, or through treatment, matters quiet down again, presently, however, to be followed by another relapse; and so on, until after weeks or months of suffering the patient dies of exhaustion or slowly recovers. This is the type of dysentery, as will be explained presently, that is generally associated with, and in all probability is caused by, a specific amœba— Amœba histolytica— and is designated "amœbic dysentery."

Recurring dysentery.— The patient has an attack of dysentery from which recovery appears to be complete. Months, or even years subsequently, without recognizable fresh exposure to infection, and during prolonged residence perhaps in a non-endemic district or country, the disease recurs, to subside and recur at intervals for several years. I have several times seen such cases. They can only be explained by assuming a remarkable capacity for prolonged latency on the part of the special dysenteric germ concerned, generally the amœba.

Chronic dysentery.— In a large proportion of cases of acute dysentery the bowel does not become absolutely healthy for a considerable time after abatement of the more urgent symptoms. On the slightest dietetic imprudence, after chill or fatigue,