34 BACTERIA, GENERAL CONSIDERATIONS, MORPHOLOGY 



typhoid, colon, and hog cholera, have a tendency to form long chains; 

 others, like the tetanus, group themselves in short chains of two or 



FIG. 20 



Streptococcus in pus, showing how the chain is formed by groups of two (diplococci). 

 The cells seen in the field are polynuclear leukocytes, with the exception of one cell, which is 

 a mononuclear leukocyte. X 1000. (Author's preparation.) 



three. Still other bacilli form long chains in which the lines of 

 division between the individual bacilli cannot be seen, so that we 

 see pseudofilaments. Certain bacilli rarely if ever form chains, but 



FIG. 21 



Various forms of bacilli: a, bacilli with sides parallel to their long axis and with ends 

 perpendicular; 6, bacilli with sides swollen or narrowed, causing irregular forms. X 1000. 

 (After Fliigge.) 



generally fall apart after division and form parallel groups. When 

 bacilli are studied in stained preparations some appear very uni^ 



