36 Bacteria 



directions of space so as to produce fours, eights, twelves, 

 etc., on the same plane, the name merismopedia has been 

 given (Fig. 2, e and /). Migula uses the term micrococcus for 

 the unflagellated tetrads, and planococcus for the flagellated 

 forms. 



If division take place in three directions of space, so 

 as to produce a cubic "package" of cocci, the resulting 

 aggregation is described as a sarcina (Fig. 2, i). 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 (Fig. 2, d). 



Cocci commonly occur in irregular groups having a fancied 

 resemblance to bunches of grapes. Such are called staphylo- 

 cocci, 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 



Fig. 3. Diagram illustrating the morphology of the bacilli: a, 6, 

 c, Various forms of bacilli ; d, e, bacilli with flagella ; /, chain of bacilli, 

 individuals distinct ; g, chain of bacilli, individuals not separated. 



i 



chains, surrounded by an incasement of almost cartilaginous 

 consistence, have been called leuconostoc. 



Bacilli. A better known, if not more important, group 

 of bacteria are elongate or "rod-shaped," and bear the name 

 bacillus (a rod) (Fig. 3). 



The bacilli present considerable variation of form. Some 

 are elliptoid, some long and slender. Some have rounded 

 ends, as B. subtilis; others have square ends, as B. an- 

 thracis. Some are large, some exceedingly small. Some 

 always occur singly, never uniting to form threads or 

 chains ; others are nearly always so conjoined. 



