SELECTED PAPERS 



- which has already been criticized above - is found here in one and 

 the same division of the genus Bacterium. 



The 10 contributions by Rahn [Rahn, 1929] and collaborators 

 [Rahn, Laubengeyer and Mansfield, 1929] to the classification of bac- 

 teria will be mentioned here firstly for their very sound, meritorious 

 criticisms of Bergey's system. For these we refer to the original papers 

 and we will only remark that it is most discouraging that since their 

 publication two new editions of Bergey's manual have appeared from 

 which it is evident that the editing committee did not pay any heed 

 to Rahn's amply documented considerations. In addition to calling 

 attention to various fallacies in Bergey's system Rahn has also given a 

 number of constructive suggestions, the most important of which will 

 be briefly reviewed here. In the first place Rahn and Laubengeyer 

 point out the close relationship between several of the Bacteroides spe- 

 cies and the Lactobacilli and propose to abandon the illdefined genus 

 by incorporating these species in the genus Lactobacillus, whilst group- 

 ing the remaining quite dissimilar species with some other genera. 

 Rahn and Mansfield then show the desirability and the feasibility of 

 collecting all polar flagellates out of the family of the Bacteriaceae into 

 a separate family Pseudomonadaceae as had already been proposed by 

 Winslow et al. in 191 7. Finally there is a plea by Rahn for a due recog- 

 nition of the intimate relation between the Streptococci and the natural 

 group of the rod-shaped lactic acid bacteria. Rahn goes so far as to 

 advocate the removal of the tribe Streptococceae from the family of the 

 Coccaceae and its inclusion in the Bacteriaceae. 



The most elaborate effort to revolutionize bacterial taxonomy in 

 later years is undoubtedly the monograph published by Pribram [ 1 933] , 

 an extension of the ideas expressed in an earlier paper [Pribram, 1929]. 

 The most radical principle introduced is the division of the bacteria 

 into three subclasses which are based chiefly on ecological considera- 

 tions. Thus the subclass Algobacteria is meant to comprise all the forms 

 adapted to a life in water, as evidenced a.o. by the motility with the 

 aid of polar flagella. The second subclass, Eubacteria, is made up of 

 those bacteria whose habitat is the animal body or complex waste 

 products of plant or animal origin. This habitat has led to forms which 

 are either immotile or motile by means of peritrichous flagella and 

 which are characterized by their ability to attack complex molecules. 

 Finally the third subclass, Mycobacteria, is adapted to a life in soil and 



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