352 SPECIFIC MICRO-ORGANISMS 



been described for typhoid bacilli. After the first week of the 

 disease, search for the bacillus is less promising. The bacilU 

 are only very rarely found in the blood or internal organs. The 

 blood of the patient agglijtinates the bacillus of Shiga in dilutions 

 of I to so or I to IOC. The mortality is about 25 per cent, but 

 variable in different epidemics. 



Horses have been immunized with cultures of B. dysenterice and 

 the serum of these animals has been found to be antitoxic as well as 

 bactericidal. Its use in treatment has given promising results 

 and seems to cause a reduction in the death rate of about 50 per 

 cent. ; 



Paradysentery Bacilli. — Flexner in 1899 isolated a bacillus 

 from cases of dysentery in the Philippines which at the time was 

 considered to be the same as the Shiga bacillus. Kruse, although 

 he found the Shiga bacillus in epidemic dysentery, found a some- 

 what different organism in "asylum dysentery" or pseud o-, 

 dysentery, which proved to be identical with the Flexner bacillus. 

 Between 1901 and 1903 a number of strains of bacilli resembhng 

 somewhat B. dysenteria were isolated by different investigators 

 from epidemics of diarrheal disorder, especially in the Eastern 

 United States. The paradysentery bacilli are indistinguishable 

 from B. dysenterice in morphology or in cultures on ordinary 

 media. They are all much less toxic to rabbits than the Shiga 

 bacillus, and they all ferment mannite with the production of 

 acid, while the Shiga bacillus does not. 



The bacteria considered in this chapter are all inhabitants 

 of the alimentary canal (mouth, pharynx, intestine) of man or 

 other mammals. They are small bacilli, Gram-negative, without 

 spores and without the ability to liquefy gelatin. They vary 

 from each other in motility, possession of flagella, possession of 

 capsules, and in their ability to form poisonous substances and 

 to ferment various carbohydrates. Media containing various 

 carbohydrates along with an indicator such as litmus to show 

 the production of acid, and contained in fermentation tubes so 

 as to measure the production of gas, are very useful in differentiat- 



