CLASSIFICATION. 23 



sion in three directions. This form resembles in appearance 

 a bale of cotton or a dice. 



Staphylococcus : the most common form, in which the cocci 

 occur in irregular groups of varying numbers and without 

 definite arrangement. The name is derived from the Greek 

 (TTayoM], and is given to this form because of resemblance to 

 a bunch of grapes. 



Streptococcus: chains of cocci. When division occurs in 

 only one direction, with adhesion or attachment of the indi- 

 vidual members, chains of varying length are formed. Some 

 authors distinguish a streptococcus longus and a streptococcus 

 brevis, that is, long chain and short chain ; and a few, a 



FIG. 6. 



_\\ x i 



_z^ 



O-x. v 



b 



a. Bacilli in pairs. 6. Single bacilli, c and d. Bacilli in threads. 

 e and /. Bacilli of variable morphology. (Abbott.) 



streptococcus conglomeratus. When the chain is. composed 

 of diplococci, it is called a streptodiplococcus. 



Ascococcus and leuconostoc are two very unusual groupings 

 of cocci. In the former the cocci are associated in globular 

 or lobulated masses held together by a firm, gelatinous, intra- 

 cellular substance. In the second variety the cocci gr/iw-in 

 chains or masses, and are surrounded or enclosed by a very 

 thick and tough gelatinous capsule. 



The bacilli (Fig. 6) are rod-shaped or filamentous bacteria, 

 motile or non-motile, flagellated or not, reproducing them- 

 selves both by fission and sporulation. They are not sub- 

 divided into groups, but exhibit considerable variation of 



