5. Other bacterial causes. Cases of dysentery have been reported as caused by _B. pyocyaneus_, streptococci, atypical _B. coli_ and organisms of the Gärtner group. In a _Pyocyaneus_ infection the color of the stools would be suggestive. This cause should be borne in mind in the dysenteric infections of debilitated children in the tropics. Some of the cases of so-called ptomaine poisoning due to members of the Gärtner group have clinical similarities to dysentery especially at the commencement of the attack. =C. Dysenteries resulting from mechanical irritants or poisonous substances.= A very interesting form of poisoning which gives rise to serious illness or death and is attended with marked abdominal pain and manifestations of dysentery is that reported from North China through the use of short lengths of bristles which are given mixed with the food. Various irritant metallic poisons as arsenic, antimony and mercury may give rise to dysenteric symptoms. In cancer and syphilis of the rectum there may be a suspicion that the process is an ordinary dysenteric one. Intussusception shows marked tenesmus with bloody rather than muco-sanguineous stools. While dysenteric symptoms may be present in the terminal stages of various chronic diseases, especially tuberculosis and cardiac affections, yet it is in chronic nephritis, leading to uremia, that we may see symptoms of a marked catarrhal or even diphtheritic colitis. CHAPTER X AMOEBIC DYSENTERY HISTORY AND GEOGRAPHICAL DISTRIBUTION =History.=—Lambl, in 1859, was the first one to note the presence of amoebae in man, these being found in the stools of a child affected with diarrhoea. It was Lösch, however, who, in 1875, first accurately described the parasite which he found in the intestinal ulcerations as well as in the stool of a patient with chronic dysentery and was able to produce dysenteric ulcerations in the dog, by injecting amoebae-containing faeces into the dog’s rectum. In 1879 Grassi noted the encysted forms of amoebae, but as he found them in well people, he denied their pathogenic importance. Cunningham found amoebae in the stools of cholera patients and Perroncito in those of typhoid cases, both of these authorities, however, viewing the question of their pathogenicity as did Grassi. This was the general attitude of the medical mind until Koch, in 1883, while investigating cholera in Egypt, was impressed with the striking penetration of amoebae in the walls of intestinal ulcers and considered that this fact favored the view that amoebae were pathogenic.