12 APPLIED BACTERIOLOGY 



as occur when solid particles are suspended in a fluid 

 medium, which is due to electrical disturbance, and generally- 

 called the ' Brownian movement.' 



The following bacilli, amongst others, have numerous 

 flagella distributed over the whole of the organism : The 

 typhoid bacillus, the bacillus of blue milk (Bacillus cyano- 

 genus), the potato bacillus (Bacillus mesentericus vulgatus), 

 the bacillus of malignant oedema, the hay bacillus (Bacillus 

 subtilis), Proteus vulgaris, etc. 



The following have only one or two flagella at the poles : 

 The Bacillus pyocyaneus, the Spirillum Finkleri, the Spirillum 

 cholerce Asiaticce, the Spirillum Metschnikovi, etc. 



The following have numerous polar flagella : The Spirillum 

 unchda, Spirillwm ruhrum, Spirillum concentricum, etc. 



The Micrococcus agilis has also several flagella, which 

 possibly arise from one point. 



Classification of Bacteria. — The task of classifying bacteria 

 is one of great difiiculty, since they are so little known, and 

 new kinds are constantly being discovered ; also, on account 

 of the polymorphic characters of many of the forms, it is 

 only possible to arrange them in a few leading groups 

 according to their shape and general characters, such as spore 

 formation, mode of growth, etc. A great many methods of 

 classification have been put forward from time to time, but 

 the only one we will give here is a modification of that 

 proposed by Hueppe, which is the simplest and most 

 practical. The classification of micro-organisms may be 

 divided into four main divisions : 



Coccacese, Bacteriacese, Leptotrichese, Cladotricheae. 



These groups may bfi again divided into groups, as 

 follows : 



Cocoacese — (1) Micrococcus, or Staphylococcus. — When the 

 cocci occur in masses like bunches of grapes, they are 

 called Staphylococci. Cocci often occur singly, sometimes 



