BACILLUS DYSENTERIC 129 



cultivation of the stools is undertaken, using as material the 

 bloody parts, mucus or shreds of membrane, in any and all 

 of which the germs abound. The development in the labora- 

 tory is comparatively simple, but to identify the species or 

 variety is anything but easy. The agglutinins in the patient's 

 blood may be tested against pure laboratory cultures of 

 known varieties, and thus a bacteriological diagnosis as to 

 the type may be made. Thus, for diagnosticating dysentery 

 we have only the feces culture and agglutination test. Since 

 the bacilli are not in tjie blood, cultures of this are not made. 



The dysentery bacillus is a short, straight, non-motile rod 

 with rounded ends. It is quite like the typhoid bacillus in 

 shape and size, but unlike this germ, does not move actively. 

 It may at times show degenerated forms. It is usually single, 

 but may be in pairs. It stains easily. It grows both ae'ro- 

 bically and anaerobically, but better under the former con- 

 ditions. Its growth upon laboratory media is also like that 

 of the typhoid bacillus. Best development occurs at 37 C. 

 or 98 F., and death results when 60 C. or 142 F. is held for 

 ten minutes. 



It resists freezing for a long time, possibly some weeks. 

 It is killed by drying only after long periods. Its resistance 

 to chemicals is practically the same as that of typhoid bacilli. 

 Animals do not contract dysentery when they take the bacilli 

 by mouth, but when germs or their toxins are introduced 

 under the skin, into the vein or peritoneum, profound intoxi- 

 cation occurs, with fall of temperature, peritonitis, diarrhea, 

 and in some cases hemorrhage in organs or body cavities. 



Dysentery Antiserum. Nevertheless, animals, notably 

 rabbits and horses, have been made to withstand large doses 

 by preparation with graded amounts. They develop sera 

 containing antisubstances to both the endo- and extracellular 

 dysentery toxins. This serum has been used therapeutically 

 in the treatment of dysentery of the tropical variety, but it 

 has not been found useful in other cases; it is made only 

 against what is called the Shiga type of dysentery bacillus. 

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