CLu\SSIFICATION OF ANAEROBIC BACTERIA 537 



fully to be avoided. The bacterial characters understood by 

 us are so elementary that we can, as yet, have no assurance 

 that we are not at times uniting types that have not the same 

 ancestry. 



It will be noted that the Committee has arranged the bacteria 

 into orders, families, and genera. Most families have also been 

 divided into tribes. The genera of the Actinomycetales have not 

 thus been arranged in tribes, because their relationships are 

 avowedly obscure. But the sporulating rods have been given 

 the very inferior position of two genera and the tribal relation- 

 ships are not expressed. This is because these organisms have 

 been so slightly studied. As Ford says in his introduction, our 

 knowledge of the spore-bearing bacteria is still in a state of 

 chaos. The sporulating organisms, at least the anaerobes, are 

 legion in species, and form a group that is to be divided and 

 subdivided. 



Whether or not the aerobic spore-bearers (genus Bacillus of 

 the Committee) form a homologous family, I am unable to say. 

 Compared with the anaerobic rods they are apparently very 

 few in number of species. Ford and his co-workers list twenty- 

 eight species which they place, on the basis of morphological 

 and gross cultural characters in nine "groups." These groups 

 would probably form as logical genera as some of the others 

 which have been recognized. 



It may be asked why tribal rank should not be assigned to 

 the anaerobic and aerobic rods instead of family rank. It would 

 seem that the group of anaerobic rods is sufficiently large, pecul- 

 iar, and important, to warrant its being given family rank. 

 Probably none of the botanical or zoological families contain 

 nearly as many species as may be found among the anaerobic 

 rods. On strict analogy with botanical and zoological classi- 

 fications the anaerobes should command an order at least, but 

 being unfortunately dogmatically confined in our classification 

 to a single class which must include all one-celled cellulose- 

 and chlorophyll-free plants that divide by simple fission, we must 

 be modest in our demands. 



