CELL GROUPINGS 41 



Still the terms thread, filament or chain are more common for 

 streptobacillus. 



Since the coccus is spherical, transverse division may occur 

 in any direction, though in three planes only at right angles 

 to each other. Division might occur in one plane only, as in 

 spirilla and bacilli, or in tivo planes only or in all three planes. 



As a matter of fact these three methods of division are 

 found among the cocci, but only one method for each par- 

 ticular kind of coccus. As a result there may be a variety 

 of cell groupings among the cocci. When division occurs in 

 one plane the only possible groupings are the same as among 

 the spirilla or bacilli. The cocci may occur in groups of two 



Fig. 45. — Streptobacillus grouping. Fig. 46. — Typical diplococcus 



grouping. Note that the individ- 

 ual cocci are flattened on the 

 apposing sides. 



—diplococcus grouping (Fig. 46), or in chains— strep)tococciis 

 groupings (Figs. 47 and 48). When the grouping is in diplo- 

 cocci the individual cocci most commonly appear as hemi- 

 spheres with the plane surfaces apposed (Fig. 46). Some- 

 times they appear as spheres and occasionally are even 

 somewhat elongated. The individuals in a streptococcus 

 grouping are most commonly elongated, either in the same 

 direction as the length of the chain or at right angles to it. 

 The latter appearance is probably due to failure to enlarge 

 completely after division. Streptococci frequently appear 

 as chains of diplococci, that is, the pair resulting from the 

 division of a single coccus remain a little closer to each 



