318 THE CLAS3IFICATI0N OF BACTERIA 



employed in most cases euphonious, and the meaning with but two exceptions 

 is unambiguous. 



The two exceptions are the terms " bacillus " and " bacterium." The term 

 bacillus means any rod-shaped organism, and the term bacterium means any 

 organism whatever in the general class of Schizomycetes. Hence, neither of them 

 is available for designating members of the two well-defined genera, Bacillus and 

 Bacterium. In these cases we have retained the customary circumlocutions, 

 "members of the Bacillus group " and " members of the Bacterium group." 



There remain a considerable number of bacteria, which cannot yet be 

 accorded a scientific name : in some cases because the available descriptions ai-e 

 not sufficiently detailed to allow us to determine their systematic relationships ; 

 in others, because the characters, as described, do not seem to warrant the 

 inclusion of the organism in any of the recognized genera. No useful purpose 

 would be served by suggesting new generic names, which would have no validity. 

 As we have emphasized above, any system of nomenclature employed at the 

 present time must be a temporary expedient, pending some form of international 

 agreement, and it appears to us that our aim should be to use those names which 

 seem most likely to be retained when such agreement is reached. When dealing 

 with those organisms which, at present, defy classification, we have therefore 

 frankly abandoned the use of a scientific name, with its conventional italic and 

 capital letter, and have employed the most convenient designation available. It 

 is unfortunate that many of these organisms have been given the generic name 

 of Bacillus. As this name is reserved for the spore-bearing aerobes, it cannot be 

 used, in the conventional form, for bacteria which do not in fact belong to that 

 genus. We have, in general, adopted the expedient of referring to Bacillus x 

 as " the X bacillus." In describing bacteria whose title to specific rank appears 

 to us doubtful, though their generic position is not in doubt, we have in some 

 cases employed a similar convention. 



We would here add a protest against the habit, which is unfortunately frequent 

 among medical bacteriologists, of coining new names for bacterial strains which 

 they have isolated, without appending an adequate description of the organism 

 or determining whether the organism in question corresponds with one that has 

 already been described. This laxity has in the past led to much confusion ; and 

 it would be greatly to the advantage of bacteriology in general if editorial authority 

 could be exerted to prevent the publication in medical or scientific journals of 

 descriptions of newly-named bacterial species, where these requirements are not 

 properly fulfilled. The existence in this country, and in America, of adequate 

 collections of type cultures provides the material for such comparisons as may 

 be necessary. 



Fig. 47 provides a summary, in chart form, of the American classification, 

 with the modifications referred to above. 



The following are the genera included in this classification, given in the order 

 in which they are listed in the chart : 



Actinobacillus.^ — Gram-negative, non-acid-fast rods, sometimes occurring in long chains 

 or in unjointed filaments. In lesions in the animal body no mycelium is formed, but at 

 the periphery finger-shaped cells or clubs may be visible. 



Type species. Actinobacillus lignieresi. 



Leptotrichia. — Thick, long, straight or curved threads, unbranched, frequently clubbed 

 at one end and tapering to the other. Gram-positive when young. Threads fragment 



