PROSPECTS FOR A NATURAL SYSTEM OF CLASSIFICATION OF BACTERIA 



especially attractive because the author starts with a clear formulation 

 of the rules, principles and laws which, according to his insight, should 

 govern bacterial systematics. 



Prevot's first law states that the general morphology enables one 

 to divide the bacterial kingdom in classes and these in orders. As 

 classes Prevot recognizes the six orders previously established by Bu- 

 chanan and a preliminary attempt is made at subdividing the first 

 class (Eubacteriales) in five orders which apparently correspond to the 

 five families of the American system. There is, however, the important 

 difference that Prevot envisages the possibility of demarcating the 

 Nitrobacteriaceae on the basis of an ellipsoidal cell form. Apart from the 

 fact that our criticism of the said family as defined in the American 

 system is not obviated by Prevot's redefinition, it seems to us very 

 doubtful whether a distinction between two groups of the fundamental 

 significance of an order can be founded on the difference between an 

 ellipsoidal and a cylindrical cell shape. The failure of such a procedure 

 is obvious if it is remembered that some of the most typical represent- 

 atives of the Bacteriaceae have originally been described as Micrococcus 

 species (Micrococcus prodigiosus, etc.). The ambiguity of the said char- 

 acter has, already a long time ago, led to abandoning Cohn's differen- 

 tiation of the genera Bacterium and Bacillus on the basis of the length of 

 the rods. 



We can pass the second law in silence. As for the third law we wel- 

 come the stress laid on the importance of the Gram-stain, especially 

 since good arguments are given for the view that the outcome of this 

 staining reaction depends on structural characters. The homogeneity 

 of a family in this respect is required by Prevot. 



The fourth law formulates that more special morphological prop- 

 erties (flagella, capsules, biometrical constants) have a generic value. 

 Why the use of these features should be restricted to these smaller 

 groups is not clearly stated, however. To us this limitation does not 

 seem justified particularly with reference to the flagellation. 



The remaining laws do not invite further comments ; we only refer to 

 our opposition to the sixth law in which Prevot restricts the use of 

 physiological characters to the delimitation of species. 



Prevot has confined himself to apply the above-mentioned principles 

 to the elaboration of a detailed classification of the Coccaceae. The out- 

 standing feature of his system as compared with previous ones is the 



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