CHARACTER OF BACTERIA 15 



division taking place about every twenty minutes. 

 The number of bacteria produced from a single parent 

 bacterium in twenty-four hours thus becomes enormous. 

 It is perfectly obvious that this rate of growth cannot 

 continue for very long, else the entire world would 

 long ago have become merely one huge mass of bacteria. 

 We shall study the conditions governing the growth and 

 multiplication of bacteria in a subsequent chapter; 

 suffice it here to say that further growth after a time 

 ceases, owing to the accumulation of waste-products, 

 the exhaustion of the food supply, etc. 



In form, bacteria are more or less spheric, rod 

 shaped, or spiral shaped. We call the first cocci (singu- 



Fig. 2. Forms of bacteria (Jordan). 



lar coccus)] the second, bacilli (singular bacillus), and 

 the third, spirilla (singular spirillum). The first group 

 is still further subdivided according to the manner in 

 which the individual organisms tend to group them- 

 selves when multiplying. Thus a large class of cocci 

 divide always in a single plane, and so give rise to a 

 string of cocci appearing like a string of beads. Cocci 

 growing in this manner are termed streptococci. In 

 another large class the organisms divide in every plane, 

 so that there is produced a mass having somewhat the 

 appearance of a bunch of grapes. Cocci growing in this 

 manner are termed staphylococci. Other cocci, on multi- 



