28 



DAIRY BACTERIOLOGY 



later, according to Migula, motile rods, while now it generally 

 denotes spore-forming rods. 



The screw-shaped bacteria, which always have polar flagellse, 

 are classified into the genera Vibrio and Spirillum. The vibrios 

 are monotrich and form single curves, being comma- shaped ; the 

 spirilla are lofotrich and more or less screw- shaped. Certain 

 spirilla are said to be able to form spores. 



Fiu. 30. Vibrio cholerce. (After Migula.) 



FIG. 31. Various Screw-shaped Bacteria, (After Fliiyye.) X 1,000. 



The above remarks may be condensed into the following tabular 

 classification into families and genera : 



Family 1. Coccaceae, or Sphere Forms. 



Genus Streptococcus, dividing in one direction. 

 Genus Micrococcus, dividing in two directions. 

 Genus Sarcina, dividing in three directions. 



Family 2. Bacteriaceae, or Rod Forms. 



Genus Bacterium, without spores. 

 Genus Bacillus, with spores. 



Family 3. Spirillaceae, or Screw Forms. 

 Genus Vibrio, monotrich. 

 Genus Spirillum, lofotrich. 



