Bacteria 39 



If division take place in three directions of space, so as 

 to produce a cubic " package" of cocci, the resulting aggre- 

 gation is described as a sarcina. This form resembles a 

 dice or a miniature bale of cotton. Few sarcinae have 

 flagella, similar flagellated organisms being called by Migula 

 planosarcina. 



If division always take place in the same direction, so 

 that the cocci remain attached to one another like a string 

 of beads, the organism is described as a streptococcus. 



Cocci commonly occur in irregular groups having a fan- 

 cied resemblance to bunches of grapes. Such are called* 



/ 



<D 



O 



Fig. 2. Diagram illustrating the morphology of the cocci : a, Coccus 

 or micrococcus; b, diplococcus; c, d, streptococci; e, f, tetracocci or 

 merismopedia ; g, h, modes of division of cocci; i, sarcina; /, coccus 

 with flagella ; k, staphylococci. 



staphylococci, and most organisms not finding a place in the 

 varieties already described are so classed. 



Cocci associated in globular or lobulated clusters incased 

 in a resisting gelatinous, homogeneous mass, have been 

 described by Billroth as ascococcus, Cocci, solitary or in 

 chains, surrounded by an incasement of almost cartilaginous 

 consistence, have been called leuconostoc. 



Bacilli. Better known, if not more important, bacteria 

 consist of elongate or " rod-shaped forms," and bear the 

 name bacillus (a rod) . These present considerable variation 

 of form. Some are ellipsoid, some long and slender. Some 

 have rounded ends, as Bacillus subtilis; others have square 

 ends, as B. anthracis. Some are large, some exceedingly 

 small. Some always occur singly, never uniting to form 

 threads or chains; others are nearly always so conjoined. 



The bacilli divide by transverse fission only, so that the 

 only peculiarity of arrangement is the formation of threads 

 or chains. In the older writings, short, stout bacilli were 



