BACTERIA. 37 



multiply by fission the resulting two organisms not 

 infrequently remain attached to each other, producing 

 what is called a diplococcus (Fig. 2, b). The diplococci 

 sometimes consist of two perfect spheres, but more often 

 show a flattening of the contiguous surfaces, which are 

 not in absolute apposition (Fig. 2, g). In a few cases, as 

 the gonococcus, the approximated surfaces are slightly 

 concave, causing the organism to somewhat resemble the 

 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 tetragenococcus, 

 while to the entire class of cocci dividing so as to pro- 

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

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



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- 

 coccus 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 

 clusters encased in a resisting glutinous, homogeneous 

 mass, the name ascococcus has been used in describing 

 them. A modified form of this, in which the cocci are 



