86 



STUDY AND IDENTIFICATION OF BACTERIA. 



motility. The three groups of organisms just described are non- 

 liquefiers of gelatin. Two intestinal organisms, the B. cloacae and the 

 Proteus vulgaris, differ in liquefying gelatin. 



Bacillus Typhosus (Eberth, 1880; Gaffky, 1884). This organism 

 may be isolated from the stools, urine and the blood of typhoid 

 patients. At postmortem it can be best isolated from the spleen, but is 

 also present in Peyer's patches which have not ulcerated. When 

 ulceration has occurred contamination with B. coli is almost sure. 

 Cultures may also be obtained from the liver. In sections made from 

 spleen the Gram negative bacilli are apt to be decolorized. Thionin, 



FIG. 33. Seventy-two hour old culture of typhoid bacillus on gelatine. 

 (Kolle and Wassermann.} 



then blotting and clearing in oil or xylol, shows the clumps of bacilli 

 lying between the cells. 



Formerly it was supposed that by the differences in the thickness of 

 the film of a colony or by its varying shades of grayish-blue, we pos- 

 sessed data of importance in differentiating typhoid from related 

 organisms. Growth on potato was also considered as affording in- 

 formation. At present, the biochemical reactions give us information 

 assisting in differentiation, and the agglutination or bacteriolytic 

 phenomena, the final diagnosis. The various plating media are con- 

 sidered under the studv of feces. 



