I I 2 BACTERIOLOGY. 



Genera : Leptothrix, Beggiatoa, Crenothrix, Phragmi- 

 diothrix. 



4. Cladothrichese. Possessing cocci, rods, threads, 

 and spirals. Thread-forms provided with false branchings. 

 Genus : Cladothrix. 



Zopf, however, does not assert that all the fission- 

 fungi exhibit this pleomorphism, nor does he 

 pretend that his classification will include all the 

 micro- organ isms described. Cohn, on the other 

 hand, was ready to admit that all the forms 

 described by him were not truly independent 

 species. These facts indicate that a need exists 

 for a thorough investigation of the whole subject, 

 and any classification at present can only be con- 

 sidered a provisional arrangement. In determining 

 the distinctions into species we must take into 

 account not only microscopical appearances of the 

 micro-organisms themselves and their physiological 

 action, but the character of their colonies in plate- 

 cultivations under a low power of the microscope, 

 and the macroscopical appearances displayed in the 

 various nutrient media. In this way, by considering 

 each individual characteristic, Koch showed that 

 the comma bacillus of Finkler was a different 

 organism from the bacillus which was present in 

 Asiatic cholera. 



Meanwhile in these pages we shall adopt the 

 classification of Zopf. It not only serves in a 

 practical handbook as a convenient form for 



