122 



BACTERIA, YEASTS, AND MOLDS 



the presence or absence of these motor hairs. They 



are known by the name of flagella. 



9 Spherical Bacteria: Cocci. 



The simplest type of bac- 

 teria consists of those that 





• ^ are in the shape of a minute 

 ^ sphere. Their size differs 



somewhat, but they are 



always extremely minute, and 



about all that can be said in 



I regard to them is that they 



# are spherical organisms, 

 sometimes possessing flagella 

 and sometimes apparently 



Fig. 48. a, cocci; b (Pseudomonas), without them. No internal 

 rods with polar flagella; c, rods structure is known. They 

 with peritrichiate flagella; <^. im- j^y^jpiy sometimes in SUch 

 motile rods. 



a way as 



to produce long chains (Fig. 49, a), 

 sometimes so as to produce groups of 

 fours or groups of eight or sixteen 

 (Fig. 49, b, c, d). The general name 

 given to spherical bacteria is coccus, and 

 to this name are sometimes prefixed ^'°' 49- Cocci, show- 



. . . mg methods or mul- 



certam other syllables to mdicate certam tipiication. a, stref- 



characters. Streptococcus is a name tocouus; b, Mkro- 



given to cocci forming chains (Fig. 49, 



a), and Micrococcus to those forming 



fours or irregular masses as at b. The term Sarcina is 



the name given to those that form solid masses such as 



shown in Fig. 49, c and d. 



coccus; c and dy 

 Sarcina. 



