BACILLUS DYSENTERIC 519 



The Harris Type of Organism. — ^This type of bacillus 

 dysenteriae was first encountered by Strong while working 

 in the Philippine Islands. It has since been encountered 

 quite frequently in the United States, especially in the 

 summer diarrheas in infants. This organism ferments 

 mannite as well as dextrose, maltose, saccharose, and 

 dextrin. 



It is only by careful observations of the reactions with 

 the different carbohydrates that it is possible by culture 

 methods to differentiate between these different strains 

 of bacillus dysenteriae, as has been shown by Hiss^ and by 

 others. 



The Agglutinability of Bacillus Dysenteriae. — ^The influence 

 of agglutinins in dysentery immune serum has also served 

 to differentiate between different types of baccillus dysen- 

 teriae. Normal serums, especially those of bovines and 

 of goats, also yield very instructive results. Variations 

 in the agglutinability of the several types of bacillus 

 dysenteriae, especially in normal serums, were first pointed 

 out by Bergey,^ and have since been noticed by other 

 investigators (see especially Park and Hiss, loc. cit.). 



The different types of bacilius dysenteriae can easily be 

 distinguished by their relative agglutinability, but in order 

 to do so animals must be rendered immune from each 

 variety and the serum of such animals employed as specific 

 reagents. When this is done it will be found that the serum 

 of an animal immunized with the Shiga type of organism 

 will agglutinate that type of organism in high dilutions, 

 say 1 : 5000, while the Harris type of organism will only be 

 agglutinated in dilutions of 1 : 200, and the Hiss-Russell 



1 Journal of Medical Research, December, 1904, viii. 



2 Ibid., 1903, V, 21. 



