Intestinal parasitism is commonly manifested by a collective group of symptoms and pathologic lesions of such a varied degree of intensity that the recognition of these disorders is often rather uncertain. Parasitic diseases, with few exceptions, have an indefinite period of incubation, their course commonly is protracted over a long period and they have, as a rule, an uncertain termination. Such is amebic dysentery, which commonly is manifested by the acute symptoms of frequent defecation, tenesmus, and mucous or bloody discharges. Not infrequently these acute symptoms may not appear until some time later in the course of the disease, or may be entirely wanting when the disturbance is mild in character. Nevertheless, the disease follows its normal course of ulceration of the mucosa of the colon, to be manifested later in the form of a diffuse and rather indefinite form of colitis. Certain parasites, such as Oxyuris vermicularis, which commonly