BACTERIA. 37 



German biscuit called a "semmel," hence biscuit- or 

 semmel-cocci (Fig. 2, //). Frequently a second binary di- 

 vision occurs, causing four individuals to remain closely 

 approximated, without disturbing the arrangement of the 

 first two. When division of this kind produces a distinct 

 tetrad, the organism is described as a tetracoccus, while 

 to the entire class of cocci dividing so as to produce 

 fours, eights, twelves, etc. on the same plane the name 

 merismopedia is given (Fig. 2, e and f). 



6990® 



/ 



(l h 



CD © 



e © 



3 



Fig. 2. — Diagram illustrating the morphology of the cocci : a, coccus or 

 micrococcus; b, diplococcus ; c, d, streptococci; e, f, tetragenococci or meris- 

 mopedia; g, h, modes of division of cocci; i, sarcina; j, coccus with flagella; 

 k, staphylococci. 



If, as sometimes happens, the divisions take place in 

 three directions, so as to produce cubical masses or "pack- 

 ages" of cocci, the resulting aggregation is described as 

 a sarcina (Fig. 2, t). This form slightly resembles a dice 

 or a bale of cotton in miniature. 



If the divisions always take place in the same direc- 

 tion, so as to produce a chain or string of beads, the 

 organism is described as streptococcus (Fig. 2, d). When 

 there are diplococci joined in this manner a strepto-diplo- 

 coccits is of course formed. 



More common than any of the forms already described 

 is one in which, without any definite arrangement, the 

 cocci occur in irregular groups having a fancied resem- 

 blance to bunches of grapes. These are called staphylo- 

 cocci, and, as it is very unusual to find cocci habitually 

 occurring isolated, most cocci not classified under one of 

 the above heads are called staphylococci. 



When cocci are associated in globular or lobulated 



