Z HILDA HEMPL HELLER 



his anaerobic strains. A natural feeling exists among sys- 

 tematists, that the description of a new-found tjrpe as a new 

 species is to be avoided unless the describer is very sure that his 

 type differs from all others. There is a fear that a description 

 carefully made will some day be discarded by a future taxono- 

 mist who finds it identical with a former description. This 

 logical attitude has bred and fostered a wholl}'^ unscientific 

 mania for identification of all new strains with organisms al- 

 ready described by others. In the case of parasites or in well- 

 known groups this procedure wiU only occasionally lead the 

 worker astray. In the anaerobic field it will do so frequently. 

 The scientific attitude relative to the taxonomic affinities of 

 anaerobic bacUli is to state the group or generic relationships 

 of the organisms and then to describe them minutely. The 

 routine bacteriologist should be content to assign an organism 

 to its proper genus. 



Colony formation in deep agar is included in the descriptions 

 of genera, but a restriction of the genera to such t3rpes of colony 

 form as are mentioned would be unwise. The definition of the 

 Gram staining reactions should not be regarded as of great value 

 in these descriptions, as the staining reactions of the organisms 

 and the technique of workers are too variable. Sugar fermenta- 

 tions may be relied upon in the case of actively growing species 

 only, and are valid only for media on which the behavior of a 

 strain is constant. The constancy of the fermentations here 

 quoted has not been verified by myself. Pathogenicity is not 

 to be taken as a criterion for admission to a genus. 



It is to be feared that bacteriological systematists who are 

 unacquainted with the anaerobic group will object to the creation 

 of so many genera as are here proposed. The Committee on 

 Characterization and Classification of Bacterial Types (1920) 

 propose but 38 genera for the orders Actinomycetales and Eubac- 

 leriales. The influence which the medical history of the science 

 of bacteriology has had on this classification is marked. Two- 

 thirds of the 38 genera recognized contain parasites. If we re- 

 gard the anaerobic bacteria as wild plants growing in soil, as we 

 have every reason for doing because of their many species, we 



