In cases of amoebic dysentery, the diarrhoeal attacks, which at times occur, are often associated with an abundance of flagellates, which may well be the cause of the complication. Cases of dysenteric diarrhoea have been reported from Gallipoli in which _Lamblia (Giardia)_ were apparently the only parasites involved. Such stools are often of a yellow ochre color. Relapses are common features of _Lamblia_ infections. _Lamblia_ is an inhabitant of the upper intestine while _Trichomonas_ and _Chilomastix_ belong to the large intestine, especially in the region of the caecum. While these last named flagellates are often found in the stools of those convalescent from dysentery there is a general opinion that they are nonpathogenic. These organisms may be present in diarrhoeal conditions in which case it is common to designate such diarrhoeas as flagellate diarrhoeas. Fantham and Porter have reported 187 cases of pure lambliasis. In diagnosis it is important to recognize the encysted _Lamblia_. These are oval cysts, about 10 × 7µ and show a curved central line, with two lateral dots. When stained these dots show as chromatin areas. These cysts may be found in the faeces in great numbers. The vegetative _Lamblia_ has 4 pairs of flagella, is about 15µ long and has a tumbling motion. Calomel alone or calomel and ipecac give good results at times. Enemata of organic silver salts may be of benefit. Porter recommends bismuth salicylate. Low has noted the tendency of lambliasis to recur and thinks many of the reported cases of cures are only temporary. His experience with bismuth, salol, thymol and cyllin has not been encouraging. It is well known that lambliasis is of rather frequent occurrence in mice and rats so that these rodents may be factors in spreading the infection through the agency of their faeces deposited about human food. Of other drugs recommended in treatment Dobell and Low have had no success with methylene blue, turpentine or beta-naphthol. These authors failed to find any increase in either large mononuclears or eosinophiles in a case of the infection. Since Lamblia inhabit the upper parts of the small intestine, it may be that the administration of drugs by the duodenal tube will prove an effective method of treatment. Owens reports successful results in the treatment of amoebic dysentery from ipecac so administered. Stiles has recommended sulphur in lambliasis. 3. Ciliate dysenteries (_Balantidium coli_).