CONSIDERATIONS INFLUENCING CLASSIFICATION 11 



Order V. Actinomycetales Buchanan, 1917. 



Order VI. Caryophanales Peshkoff, 1940. 



Order VII. Beggiatoales Buchanan, 1956. 



Order VIII. Myxobacterales Jahn, 1911. 



Order IX. Spirochaetales Buchanan, 1918. 



Order X. Myco-phismatales Freundt, 1955. 

 Class III. Microtatobiotes Philip, 1955. 



Order I. Rickettsiales Buchanan and Buchanan, 1938, emend. Gieszczy- 

 kiewicz, 1939. 



Order II. Virales Breed, Murray and Hitchens, 1944. 

 Division II. Thallophyia Endlicher, 1836. 

 Division III. Bryophyta Haeckel, 1866. 

 Division IV. Pteridophyta Haeckel, 1866. 

 Division V. Spermatophyta Goebel, 1882.* 



It has been felt desirable to subdivide the Order Eubacteriales, as defined in 

 the 6th edition of the Manual, into Order I, Pseudomonadales, which includes 

 all of the polar-flagellate types of true bacteria, and Order IV, Eubacteriales, 

 which includes the peritrichous types of true bacteria. As in the 6th edition, the 

 photosynthetic purple and green bacteria that are polar flagellate have been 

 included in the order with the colorless polar-flagellate bacteria. This arrangement 

 emphasizes a concept first introduced into the classification of bacteria by Migula 

 (Arb. Bact. Inst. Karlsruhe, 1, 1894, 235-238). This concept is analogous to the 

 concept used by protozoologists who recognize the orders Flagellata and Infusoria 

 in Protozoa. 



Bacteriologists have recognized differences between polar flagellate and 

 peritrichous bacteria ever since Migula emphasized them, but there has always 

 been a residual protest against drawing a sharp line between the two groups of 

 bacteria. While there is good reason to draw a sharp line between the ordinary 

 polar flagellate types of bacteria and the peritrichous types, there are certain 

 groups such as legume nodule bacteria {Rhizobium) , the violet bacteria {Chromo- 

 bacterium), the agrobacteria (Agrobacterium) and certain motile forms placed in 

 the family Corynebacteriaceae that present a type of peritrichous flagellation that, 

 when studied superficially, is misleading. Some cultures of these organisms are 

 found to show only a single flagellum, while others closely related to these 

 monotrichous species show several flagella peritrichously arranged. On casual 

 examination these conditions appear to form a transition between the two types 

 of flagellation. However, this clearly is not the case. This apparently intermediate 

 type of flagellation seems to be a comparatively recent development in which 

 the flagella of certain peritrichously flagellated species have undergone a retro- 

 gressive specialization. In this the organisms have become primarily dependent 

 on one flagellum as their chief organ of locomotion. They therefore are included 

 in Order IV, Eubacteriales, with other peritrichous bacteria. 



* Goebel, K., in his edition of Sach's Grundziige der Systematik und speciellen Pflanzen- 

 morphologie, p. 334, 1882, was apparently the first author to use this name, although he 

 used the incorrect spelling Spermaphyta. 



