EXPERIMENTAL INOCULATION 357 



exception of one case recorded by Rosenthal the organism has never been 

 found in the blood stream : according to some observers it is occasionally 

 present in the mesenteric glands (Shiga, Duval and Bassett, [Aveline, Boycott 

 and Macdonald]). 



[Aveline, Boycott and Macdonald isolated the organism from the spleen 

 in one out of three fatal cases of asylum dysentery. ] 



Several varieties of dysentery bacilli have been described, differing from 

 one another in one or more particulars and especially in their action upon 

 sugars. For practical purposes these varieties may be divided into two 

 types : the Shiga-Kriise or non-mannite fermenting type and the Flexner 

 or mannite fermenting type (see also p. 360). 



Some authors regard the differences between these two types as sufficient 

 to justify their classification as separate species. But it is held that these 

 differences are not marked enough to warrant so complete a separation, and 

 the view put forward by Gay and Duval which is perhaps of the nature of a 

 compromise, commands general acceptance. These authors consider that 

 the bacilli causing bacillary dysentery are to be regarded as belonging to a 

 group of organisms exhibiting certain variations among themselves rather 

 than as a single sharply-defined species. There is a similar multiplicity of 

 varieties of the causal organism of cholera, as will be shown later. 



The Shiga type of bacillus is the common cause of dysentery, and it will 

 be therefore described at length in the following pages, the points of difference 

 between it and the Flexner type being noted in the proper places. The 

 general statement may here be made that all strains of Shiga 's bacillus agree 

 in their cultural and other characteristics, while under the title of Flexner's 

 bacillus a number of very closely related though not absolutely identical 

 organisms are included. 



SECTION I. EXPERIMENTAL INOCULATION. 



Shiga bacillus. 



Speaking generally, the Shiga type of bacillus is much more highly patho- 

 genic to laboratory animals than are bacilli of the Flexner type. 



Infection by the alimentary canal. In man. Strong and Musgrave after 

 administering some bi-carbonate of soda to a condemned criminal gave him 

 a two-day-old broth culture of the dysentery bacillus. After an incubation 

 period of 36 hours the man suffered from a typical attack of dysentery with 

 blood-stained stools from which he made a rapid recovery. The bacillus was 

 isolated from the stools. 



In animals. Infection of the alimentary canal whether by feeding or 

 inoculation generally gives negative results (Rosenthal, Shiga, Conradi, and 

 others). 



After feeding guinea-pigs with dysentery bacilli, however, Chantemesse found 

 lesions in the intestines similar to those seen in human dysentery ; and Shiga, after 

 introducing a culture into the stomach of a cat, noticed that it suffered from mucous 

 diarrhoea and found the bacilli in increased numbers in the stools. Kazarinow 

 introduced very large quantities of culture into the intestines of rabbits by means 

 of an cesophageal sound, and post mortem found characteristic lesions in the 

 intestine. 



Intra-peritoneal inoculation. Inoculation of dysentery bacilli into the 

 peritoneal cavity is rapidly fatal to most animals. Post mortem, the peri- 

 toneal cavity contains a blood-stained serous exudate and the intestine is 

 very markedly hypersemic but presents none of the lesions characteristically 

 seen in the human disease. 



