THE BACTERIA AND VIRUSES 



347 



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Fig. 336. — Staphylococcus aureus. Cells in clusters. 

 Gram stained. 



Rod-like organisms are given the general name of bacillus (Fig. 337), 

 though this name properly belongs only to one genus of the rod Bacteria. 

 If the rod is curved it is placed in the genus Vibrio, or, if spirally twisted, 

 in the genus Spirillum. Along with these are normally classed the 



Fig. 337. — Bacillus anthracis. Mass of bacillary rods in 

 kidney tubule of mouse. Gram stained. The causative 

 organism of anthrax. 



spirochaetes (Fig. 338), with long, thin, wavy bodies, though their inclusion 

 among Bacteria is questionable. 



Bacteriology was for so long in the hands of men whose interests were 

 primarily medical that the classification was unsatisfactory until an American 



