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deepen by continued microbic action and even penetrate through into the peritoneum, leading to peritonitis, or gangrene may set in in the damaged necrosed tissue, and in either case death follows unless surgical intervention is early. Repair proceeds along the same lines as in amoebic cases, but, the ulcers being generally more superficial, the permanent damage is not so great.

The stools have a characteristic microscopic appearance, as numerous pus epithelial cells and large macrophage cells are present 'in the mucus. Macroscopically the stool most often consists of mucus, like cloudy-grey jelly streaked or stained by bright red blood, or the mucus may be bile-stained in a diarrhoea-like stool or, in very severe cases, there are shreds of necrosed mucosa.

The causal bacillus is readily isolated by culture within the first days, but afterwards it becomes difficult as the microbic life in the necrotic tissue becomes a flora of proliferating organisms. The bacillus of Shiga, which has been the only species isolated from the blood stream, has been found therein in only four or five cases. The bacilli dysenteriae, as judged by post-mortem findings, pass to the mesenteric glands along the lymphatics, but are arrested there. After the cessation of the symptoms the percentage of cases retain- ing the causal organism in the bowel is very small, as testified in the figures given above. If the patient becomes a carrier of B. dys. Shiga the stools will continue to be in part muco-purulent, even up to three or more years. The property of agglutinating the causal organism and other strains of the same race is present in the blood after the first week and may last for only eight or ten days in mild cases, but when the infection is prolonged this property of agglutination per- sists for a longer period. B. dys. Shiga infected cases generally agglutinate also the B. dys. Flexner-Hiss in a lesser degree, but the converse does not hold. B. dys. Flexner-Hiss cases agglutinate sev- eral species of the group, rarely only the strain isolated from them. B. dys. Schmitz cases do not appear to develop agglutinins even for their own organism.

The general and symptomatic treatment given above for amoebic dysentery is similar, but the specific treatment widely variant, and this is directed towards neutralizing the toxins which further the clinical symptoms. It is the anti-Shiga serum, prepared by in- oculating the bacilli with their contained endotoxins into the horse, which is the most efficacious; and as it is the infection with B. dys. Shiga which is most severe, its utility is considerable. It has been employed also in cases due to B. dys. Flexner-Hiss with apparently satisfactory results. A polyvalent horse anti-serum made by inoculating strains of both these groups has also been extensively given in cases of either infection and, with this, amelioration of symptoms has followed. The injection of anti-serum should be as early in the illness as possible and in large doses dependent upon the severity of the cases, e.g. 60 c.c., 40 c.c., 20 c.c., on successive days in a severe case; and with this treatment free saline purgation is combined until the stools become faecal. Thereby rapid ameliora- tion follows, complications are rare, and the bacillus quickly elim- inated from the body. In the early complications of bacillary dysen- tery anti-serum therapy again gives good results.

The general prophylactic measures to be taken are comparable to those against infections with E. hislolytica, but it should be remembered that bacilli are lower vegetable organisms and can

proliferate in suitable environment outside the body. Dependent on several factors, bacillary is more contagious than amoebic dysentery. Encouraged by successful results following inoculations of typhoid and paratyphoid vaccines, some series of inoculations with a vaccine of B. dys. Shiga were made in epidemic areas during the war, as this was the bacillary organism so prevalent and so toxic in epidemics during war conditions. Its contained toxins give rise to acute local reactions unless modified prior to inoculation by special methods, as by laving the heat-killed bacilli with normal serum (serum-treated) or with specific horse anti-serum (sensitized), or by inoculating both specific anti-serum and bacillary emulsions on approximating days, or by giving an absorbed specific anti-serum and bacillary emulsion simultaneously, or by emulsifying the bacilli in oil. The series of inoculations made by various workers gave encouraging results. Vaccine-therapy employed to rid the convalescent carrier of B. dys. Shiga has not been successful. In striking contrast with B. dys. Shiga the killed and untreated emulsions of the B. dys. Flexner- Hiss group give rise to no reaction, even in high doses.

Spirochaetic Dysentery, due to Spirochaeta eurygyrate (Le Dantec 1900, Werner 1910, Fantham 1916). Investigation of this type of dysentery is in continued progress, and evidence is increasing that this spirochaeta is capable of living upon the mucous membrane of the large bowel and maintaining a chronic form of dysentery. It is seen in considerable numbers in the mucus and occasionally also within the lining cells of the glands. Occasionally there is also blood present with the mucus which is being continually passed with faeces. An acute condition with passage of blood and mucus only has been observed. This spirochaeta is resistant to intravenous injections of neosalvarsan or tartar emetic alone ; and treatment by an arsenic-containing compound at the same time as a local washing of the bowel with irrigations containing eucalyptus has given the most encouraging results.

Helminthic Dysentery. The chief helminths which give rise to dysentery are the bilharzia worms, Schistosoma mansoni, in Africa, South America, West Indies, and Schistosoma iaponicum in the Far East. Bilharzia dysentery is characterized by the passage of mucus and clots of blood due to the presence of the ova which the adult female worm lays in the capillaries of the wall of the rectum. This form of dysentery is extremely common in Egypt. The discov- ery of the intermediate snail host and the specific action of sodium or potassium tartrate in killing these worms in man is an advance of considerable value.

Other trematodes which may cause dysenteric symptoms are Fasciolopsis buski, Heterophyes heterophyes and Paragonimus wester- manni. Normally the last is a lung fluke, but it occasionally occurs in cysts of the intestinal wall, when it gives rise to the passage of blood and mucus in the stools.

In heavy infections with hook-worm (Ancylostoma duodenale,

C resent in England in the mines of Cornwall, and Necatpr americanus) lood and mucus are sometimes passed in large quantities, and these cases may be mistaken for true dysentery. Thymol given orally rapidly kills off these worms.

Ciliar Dysentery, due to Balantidium coli and known to occur in Japan and the Philippine Is., is rare elsewhere and needs but men- tion. A specific remedy has not yet been found. (W. B. A.)