390 MANUAL OF BACTERIOLOGY. 



artificial in one place in the article referred to, Ford states in another place, 

 that the failure to agglutinate with dysenteric serum positively differentiates the 

 B. pseudodysentericus from B. dysentera. 



Below are some of the characteristics noted by Ford.* 



Bacilli measuring 0.5 by 1-2 microns in dimensions; in pairs and short chains. 

 Slow motility in young broth and in agar cultures, motility more marked in older 

 cultures. Spores absent. On agar slant growth confined to the line of inocu- 

 lation. Deep colonies in agar round, regular and opaque. In general the 

 colonies resemble those of B. typhosus. Growth in broth abundant with heavy 

 sediment, but no pellicle. On gelatin no liquefaction. Fennentation in dex- 

 trose broth grow in both arms of the tube, reaction in closed arm, acid; no gas. 

 Indol produced rarely in small quantities. It is found in the lower portions of the 

 intestines, but also occurs in the stomach and duodenum as well, in persons 

 not affected with dysentery. Does not agglutinate with the serum from 

 persons suffering with dysentery. 



Torreyf summarizes the points of difference between the true dysentery 

 bacillus and the pseudo-forms as follows: The latter spread over the surface 

 of the culture plate mere than the B. dysentericus, .they produce finally acidity 

 in litmus milk, do not absorb agglutinins of B. dysentericus. The realtionship 

 between the B. dysentericus and the pseudo-forms is about the same as that 

 existing between the B. diphtheria? and the pseudo-diphtheria bacilli. 



Spirillum Cholerae Asiaticae (Comma Bacillus of Cholera). 

 A rod-shaped organism, with rounded ends. It is usually 

 curved, hence the name comma bacillus often given to it; but 

 the curve is often very slight. The curved forms, placed end 

 to end, may produce an S-shaped body. The length is from 

 0.8 to 2 ft and the breadth from 0.3 to 0.4 /*. In cultures some 

 individuals may develop into genuine spirilla. In the whitish 

 particles found in the stools of cases of cholera the organisms 

 may be present in very large numbers. In these particles they 

 may exhibit a very curious arrangement, lying parallel with 

 one another, and, as remarked by Koch, they resemble a 

 school of fish moving up stream. Involution forms, irregular 

 in outline and staining poorly, are often seen in old cultures. 

 The organism is motile, having a flagellum at one end. It does 

 not form spores. It stains with the ordinary aniline dyes, but 

 not by Gram's method. It is aerobic. It grows at the room- 

 temperature, but better in the incubator. On the ordinary 

 media the growths are whitish. It grows best on neutral or 



*Loc, cit. 



"fJourn. Exper. Med. Vol. VII. 1905. pp. 365-400. 



