316 THE CLASSIFICATION OF BACTERIA 



names B. typhosus, B. pestis, B. anthracis, and B. tuberculosis, has obtained very 

 poor value for liis effort. If, adopting a more rational nomenclature, he memorizes 

 the names Salmonella typhi, Pasteurella pestis, Bacillus anthracis, and Mycobacterium 

 tuberculosis, he will, when he has studied the groups concerned, have a very useful 

 picture of each of these organisms as typifying a separate genus ; and the fact 

 that some other organism is called Salmonella enteritidis, or Pasteurella aviseptica, 

 or Bacillus subtilis, or Mycobacterium phlei, will convey to him some knowledge 

 of its salient characteristics. 



We are, ourselves, convinced that the correct approach to bacteriology, irre- 

 spective of the particular field in which the student intends ultimately to work, 

 is to gain some knowledge of bacteria as living things ; and such knowledge can 

 most easily be obtained by grouping like forms together for the purposes of study, 

 comparing them with other groups, and noting the differences and resemblances. 

 For these groups we need names, even if they must, for the moment, be regarded 

 as provisional. 



This requirement can be fulfilled by adopting one of the several systems of 

 classification and nomenclature that have been advocated within recent years. 

 This is quite definitely a policy adopted faute de mieux. None of these systems 

 has received any official or international sanction. As Buchanan, Breed and 

 Eettger (1928) point out, neither of the systems drawn up by committees appointed 

 by the Society of American Bacteriologists has been officially approved by that 

 Society. The selection of one of the existing systems therefore remains a matter 

 of personal choice ; and, whichever system is selected, there is no reason to 

 suppose that it, or the nomenclature based upon it, will receive international 

 sanction without modification. 



The terms " genus " and " species," as applied to bacteria, seem to us to defy 

 definition, except as designations for two convenient groupings, of which the 

 genus is the larger including group, and the species the smaller included group. 

 For this reason, and because of the absence of any form of international agree- 

 ment, we doubt the usefulness, at the present time, of naming orders, families, 

 sub-families, and tribes. Nor do we feel that the time is ripe for the creation 

 of large numbers of genera, or for the erection of an inelastic system into 

 which all known varieties of bacteria are to be forced, each with its appropriate 

 label. 



It appears to us that the classification advocated in the final report of the 

 first American Committee (1920) offers a carefully constructed scheme on which 

 a useful nomenclature can be based, and that it has been designed on general 

 lines which most bacteriologists would regard as sound ; moreover, the Committee 

 themselves make no claim to finality, and are at pains to indicate the tentative 

 nature of some of the groupings they suggest. 



We have therefore adopted the system of nomenclature set out in the final 

 report of the first American Committee (Winslow et al. 1920), with a few minor 

 modifications. We have merged the genus Diplococcus in the genus Streptococcus, 

 since it appears to us that the pneumococcus should be included in the latter 

 group. We have adopted the genus Brucella, which has already received un- 

 official recognition from many bacteriologists ; since the group which contains the 

 bacillus of Malta fever, and the bacillus of bovine abortion, appears to have as 

 good a title to generic rank as the group which contains the plague bacillus and 

 the bacilli causing hsemorrhagic septicaemia in animals, though we frankly admit 



