42 PATHOGENIC BACTERIA. 



Colin divided the bacteria, according to their mor- 

 phology, into — 



Sphero-bacteria, or cocci ; 

 Micro-bacteria — short rods ; 

 Desmo-bacteria — bacilli ; 

 Spiro-bacteria — spirilla. 



It has even been suggested to classify the bacteria by 

 the size and number of their flagella, of which so little 

 is known. 



The most convenient classification, though it cannot 

 be purely scientific, seems to be the morphological one 

 based upon that of Colin. 



I. Cocci, ] 



II. Bacilli, \ monomorphous forms of the lower order. 



III. Spirilla, i 



IV. Beggiatoa, 

 V. Thiothrix, 



VI. Leptothrix, j- pleomorphous forms of the higher order. 

 VII. Cladothrix, 

 VIII. Streptothrix, J 



