SELECTED PAPERS 



nomenclature for all genera, fully independently of the principle of 

 priority. 



On the other hand, it is not surprising that the manifest neglect of 

 the importance of morphological characters other than the flagellation 

 has given rise to severe criticism. Without entering into a discussion 

 of the numerous objections raised, it may suffice to give here a few 

 examples in which in consequence of this the principles of natural 

 relationship have been violated. The place of the immotile groups in 

 the system is not satisfactory. Here physiological characters, like special 

 nitrogen requirements, have been decisive in the position of the genera 

 Streptococcus, Caseobacterium, and Propionibacterium amongst the Peritri- 

 chinae, in the position of Mycomonas, Corynemonas and Actinomyces 

 amongst the Cephalotrichinae. The reason for this is that Orla-Jensen 

 has adopted the view that one and the same physiological evolution 

 has occurred only once in phylogeny. The possibility is not considered 

 that such an evolution may have taken place independently in various 

 morphologically different groups. 



Morphologically the three first mentioned genera show such close 

 affinities to the genera Mycobacterium and Cory neb acterium, that the 

 grouping of these five genera in the two different orders is inaccept- 

 able. In addition the designation of the two last mentioned genera as 

 Mycomonas and Corynemonas, thus suggesting a relationship between the 

 representatives of these groups and the cephalotrichous genera, has its 

 foundation exclusively in the oxidative character of their katabolism. 

 Here again we encounter the idea that in determining the systematic 

 position of a group metabolism dominates over morphology. 



Another instance of artificial grouping is offered by the creation of 

 the genus Carboxydomonas for the permanently immotile Bacillus oligo- 

 carbophilus discovered by Beijerinck and Van Delden. The systematic 

 position given to this organism by Orla-Jensen - also expressed in its 

 new generic name - is merely based on the idea, that there is a close 

 resemblance between the metabolism of the organism in question and 

 that of the representatives of the genera Hydrogenomonas and Methano- 

 monas. Morphologically, however, the species of the latter genera are 

 so typically related to the Pseudomonas species and so distinctly different 

 from B. oligocarbophilus that Orla-Jensen's classification has to be 

 rejected. 



In spite of the criticisms given we want to emphasize that in our 



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