Wenyon noted a case of coccidial infection (_Isospora hominis_) in which there was a dysenteric syndrome. There have been about seventy cases of infection with this parasite reported, chiefly from soldiers serving in Gallipoli. The usual opinion is that they are nonpathogenic parasites. The oocysts are ovoid, with one end narrowed, and measure 28 × 14 microns. There are two sporocysts, each of which contains four sporozoites. The cyst when first passed is unsegmented. _Helminthic dysenteries._—1. In addition to the protozoal causes above noted we may have dysenteric symptoms following infections with trematodes, especially _Schistosoma mansoni_ and _S. japonicum_. In these cases we have mucus coating the stool with more or less clotted blood in which mucus we may find the diagnostic ova. A rather high eosinophilia is present. 2. Infections with _Gastrodiscus hominis_ also give rise to dysenteric manifestations. 3. A very small cestode, _Heterophyes heterophyes_, has been noted to cause a condition suggestive of dysentery. 4. In 1902, Brumpt noted the finding of a nematode, _Oesophagostomum brumpti_, in the large intestine of an African native, which caused dysenteric symptoms and, more recently, another species, _O. stephanostomum_, has been reported as causing a fatal dysentery in a Brazilian at Manaos. 5. There have also been reported cases with dysenteric manifestations which were apparently connected with intestinal myiasis. =B. Dysenteries caused by bacteria.= 1. Those caused by either the more toxic, nonacid mannite strain of Shiga, or the less toxic, acid mannite strains of the Flexner group. 2. Morgan has reported as the cause of certain bacillary dysenteries a bacillus known as B. Morgan No. 1. It is motile, produces indol, and in glucose bouillon gives a very slight amount of gas. It does not change mannite and does not produce a primary acidity in litmus milk. This organism is a frequent cause of summer diarrhoea of children. Flies from houses with such cases often show Morgan’s bacillus. Paratyphoid infections may give the clinical picture of a colitis and such cases at times show a large amount of blood in the dysenteric stools. Usually the symptoms are rather those of an entero-colitis or a gastro-enteritis. 3. In Japan, dysentery-like epidemics of a very fatal disease, termed _ekiri_, occur among young children. The organism is very motile, producing gas and acid in glucose, but not in lactose media. It is reported at times to show indol production. Apparently a member of the Gärtner group. 4. Spirillar dysentery. LeDantec has reported a type of dysentery which shows the presence of great numbers of spiral forms. These are Gram negative and noncultivable. It is in question whether they belong to the bacteria. There is no fever in this type of dysentery.