MORPHOLOGY AND RELATIONSHIPS OF MICROORGANISMS 29 



be produced by the breaking up of chains of streptococci into 

 pairs. 



Cocci sometimes divide in three planes at right angles to each 

 other. This results in the formation of cubes or packets of cocci. 

 A packet of this kind is called a sarcina (pi. sarcince). 



0. 



Fig. 5. Shapes and groups of cocci: 1, Single coccus (micrococcus) ; 2, 

 cocci in an irregular mass (staphylococcus) ; 3, spheric diplococci; 4, flat- 

 tened diplococci; 5, coffee-bean-shaped diplococci; 6, lanceolate diplo- 

 cocci; 7, streptococcus with short chains; 8, streptococcus with long 

 chains; 9, a streptococcus made up of diplococcus elements; 10, cap- 

 sulated micrococci; 11, sarcina. 



A staphylococcus (pi. staphylococci) is a coccus whose planes 

 of division are not at right angles, or which divides at different 

 intervals with a consequent irregular grouping of the cells much 

 resembling grapes in a cluster. 



Fig. 6. Types of bacilli. 



Bacilli occur either singly or in chains. The latter are some- 

 times known as streptobacilli. 



Spirilla usually occur singly, although short chains of two or 

 three individuals are sometimes observed. 



In a few bacteria the gelatinous envelop of the cell is greatly 



