346 TYPHOID FEVER 



BACTERIA IN DYSENTERY. 



Dysentery has for long been recognised as including a number 

 of different pathological conditions, and within more recent times 

 amoebic and non-amoebic forms have been distinguished. Of the 

 latter bacteria have been believed to be the causal agents, and an 

 organism described by Shiga in 1898 has almost certainly been 

 established as the cause of a large proportion of cases. Shiga's 

 observations were made in Japan, and confirmatory results have 

 been obtained by Kruse in Germany, by Flexner and by Strong 

 and Harvie in the Philippine Islands, and more recently by Vedder 

 and Duval in the United States. It is now further recognised 

 that the epidemics of dysentery which from time to time occur 

 in lunatic asylums are usually due to bacilli of this type, and in 

 America the organism has been demonstrated in the summer 

 diarrhoea of children. The evidence for the relationship of the 

 organism to the disease consists chiefly in the apparently con- 

 stant presence of the organism in the dejecta in this form of 

 dysentery, and the agglutination of the organism by the serum 

 of patients suffering from the disease, but confirmatory evidence 

 has also come from animal experimentation. From different 

 epidemics a great many different strains of the dysentery bacillus 

 have been obtained, but these all possess common characters and 

 are undoubtedly closely related to one another. The various 

 strains resolve themselves into two chief groups, whose differences 

 lie in their behaviour towards certain sugars, in their capacities 

 of originating indol and in their agglutinating reactions. The 

 relation of amcebaB to dysentery will be discussed in the 

 Appendix. 



Bacillus Dysenteriae (Shiga}. Morphological Characters. 

 This bacillus morphologically closely resembles the typhoid 

 bacillus, but is on the whole somewhat plumper, and filamentous 

 forms are comparatively rare. Involution forms sometimes occur, 

 especially in glucose agar. Most observers have found no trace 

 of motility, whilst others say that it is slightly motile. Vedder 

 and Duval have, however, by a modification of Van Ermengen's 

 process, demonstrated in the case of one strain the presence of 

 numerous lateral flagella, which are of great fineness, but of 

 considerable length. No spore formation occurs ; the organism 

 is stained readily by the ordinary dyes, but is decolorised by 

 Gram's method. 



Cultural Characters. In these also considerable resemblance 

 is presented to the typhoid bacillus. In gelatin a whitish line of 

 growth occurs along the puncture, but the superficial film-like 



