44 INFECTIOUS AND PARASITIC DISEASES. 



To the cocci, or micrococci (sing., coccus) — belong 

 the dots or spherical forms. 



Fig. I. — Staphylococci. Streptococci. Diplococci. Tetrads. Sarcinae. 

 ^ . : '^ ■ (Williams.) 



To the bacilli (sing., bacillus) — the dash-like or 

 rod-shaped bacteria; and to the 



» 



Vi 



Fig. 2. — Bacilli of Various Forms. (Williams.) 



Spirilla (sing., spirillum) — the spiral, corkscrew, or 

 comma-shaped forms. 



> V 4/ 



Fig. 3.— Spirilli of Various Forms. (Williams.) 



Certain of the bacteria exhibit a singular 

 Grouping. arrangement to each other, when examined 



on a slide under the microscope, that is 

 peculiar and constant. This is found in the group 

 micrococcus. It is due to the manner of multiplication ; 

 the bacilli and spirilli multiply by division through 



