MODE OF MULTIPLICATION 67 



To the spirilla belong the bacteria that are curved when 

 seen in short segments and that appear as undulating 

 threads when such segments are of greater length or when 

 several short segments are joined end to end. (See Fig. 4.) 



FIG. 3 



d e f 



a, bacilli in pairs; b, single bacilli; c and d, bacilli in threads; e and /, 

 bacilli of variable morphology. 



The micrococci are subdivided according to their pre- 

 vailing mode of grouping, as seen in growing cultures, into 

 staphylococci those growing in masses like clusters of grapes 



FIG. 4 



a b c 



a and c, spirilla in short segments and longer threads the so-called comma 



forms and spirals; 6, the thick spirals, known as vibrios. 



(see Fig. 2, a); streptococci, those growing in chains con- 

 sisting of a number of individuals strung together like 

 beads upon a string (see Fig. 2, b) ; diplococci those growing 



