SELECTED PAPERS 



in the building up of the system in the most arbitrary way. The result 

 is a complete lack of homology in the various groups, as has already 

 been emphasized by Prevot [I.e.). In addition to this serious short- 

 coming an utter disregard for the significance of mutual relationships 

 between natural groups is apparent. 



In support of these statements the following instances may be cited. 

 The first one of the five families of the order Eubacteriales, viz., the JVitro- 

 bacteriaceae, is a curious conglomerate of organisms the majority of 

 which have nothing in common save the fact that the average - usu- 

 ally medically trained - bacteriologist is unfamiliar with them. Where- 

 as Buchanan, in creating this family, clearly intended to separate the 

 nitrifying bacteria with their remarkable autotrophic mode of life 

 from those bacteria for which organic substances are a necessary pre- 

 requisite for their development, this principle was violated when the 

 Committee included in this family organisms which 'may use in their 

 metabolism' also 'simple carbon containing compounds'. Apart from 

 the question what one has to understand by the restriction 'simple' it 

 will suffice to remark that nearly all bacteria will answer this require- 

 ment. Nor can such a 'simple' metabolism have been meant to be im- 

 perative since any bacteriologist acquainted with genera like Aceto- 

 bacter and Rhizobium will cultivate representatives of the genera in 

 media containing an abundance of complex organic compounds! 



The next family, Coccaceae, shows a clear-cut example of lack of 

 homology in its subdivision in genera. No argument whatever is ad- 

 vanced for the sudden use of the character of pigment formation in 

 the demarcation of the genus Rhodococcus. This emphasis on the occur- 

 rence of a red pigment in representatives of this genus, although noth- 

 ing is known about a possible metabolic significance of the pigment, is 

 most astounding, since the occurrence of a yellow or even an orange 

 pigment amongst members of the genus Micrococcus does not seem to 

 offer any ground for separating these from the non-pigmented species. 



Proceeding to the third family, Spirillaceae, we will only point out 

 that here again we meet with an instance where the occurrence of a 

 red pigment is not considered of sufficient importance to be used as a 

 generic character, for Spirillum rubrum Esmarch is classified together 

 with the colourless spirillae. Unfortunately in this case - and this in 

 contrast to what has been remarked regarding the Rhodococcus species - 

 there would have been every reason for separating Sp. rubrum from the 



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