Mr C., who has lived for ten years in the tropics, was under the care of Dr de Jong and myself for chronic amoebic dysentery. Some five years ago he suffered from an abscess of the liver, readily cured after operation. Before this abscess he had never noticed any dysenteric symptoms, but afterwards he often had mild, or sometimes more severe, attacks of recurring dysentery, most times without fever. During the attacks, the bloody slime contained a great number of amoebae, principally of Entamoeba histolytica and containing erythrocytes. With an “emetine cure” the attacks regularly subsided; but between two attacks the patient produced constantly a great quantity of so-called “minuta forms” and 4-nucleate (“tetragena”) cysts of this species in the faeculent parts of the stools. After an emetine treatment I often found a rather sudden increase in the number of cysts (always measuring from 11·5–13·5μ), sometimes to a tremendous amount. Several times we tried to get rid of the amoebae by a cure with emetine bismuthous iodide, but without success, so the patient stayed under observation and regularly sent us his stools for control.