10 Dairy Bacteriology. 



each cell into two cells through the formation of a divi- 

 sion wall across the cell. The new cells divide and the 

 plant or animal continues to grow. The same cell divi- 

 sion occurs in the bacteria but since the bacteria are 

 single celled, division of the cells means an increase 

 in numbers rather than growth as in the higher forms 

 of life. 



In the case of those bacteria that have a greater length 

 than diameter, the new wall is formed at right angles 

 to the long axis of the cell. As soon as the division is 

 complete each cell is a complete individual, capable of 

 carrying on all of its life processes. The cells may, how- 



FIG. 2. DIVISION OF BACTERIA. 



The bacteria increase in numbers by the division of .each cell 

 into two cells. (After Novy.) 



ever, cohere and thus form distinctive groupings that 

 may serve to identify certain types. Some of the cocci 

 form long chains and the term streptococcus is applied 

 to such. Other groupings may be similar to a bale of 

 twine or they may be massed in clusters with no regu- 

 larity distinguishable. 



Spores. Just as ordinary plants form resistant struc- 

 tures, known as seeds, capable of retaining vitality un- 

 der conditions unfavorable for growth thereby perpetu- 

 ating the species, so with certain of the bacteria, definite 

 structures, known as spores, that are analogous in some 

 respects to the seeds of the higher plants, are produced 

 within the mother cell. The spores are exceedingly re- 



