52 CLASSIFICATION OF BACTERIA 



Genus 3. Fusiformis. Obligate parasites. Anaerobic or micro- 

 aerophilic. Cells frequently elongate and fusiform, staining some- 

 what unevenly. Filaments sometimes formed; non-branching. 

 Non-motile. No spores. Growth in laboratory media feeble. 

 T}^pe species, Fusiformis termitidis Heelling. 



Genus 4. Pfeifferella. Non-motile rods, slender, Gram-nega- 

 tive, stain poorly, sometimes forming threads and showing a ten- 

 dency tow r ard branching. Gelatin may be slowly liquefied. Do 

 not ferment carbohydrates. Growth on potato characteristically 

 honey-like. Type species, Pfeifferella mallei. 



E. Order Eubacteriales. The order Eubacteriales includes the 

 forms usually termed the true bacteria, that is, those forms which 

 are considered least differentiated and least specialized. The cell 

 metabolism is not primarily bound up with hydrogen sulphid or 

 other sulphur compounds, the cells in consequence containing neither 

 sulphur granules nor bacteriopurpurin. The cells apparently do not 

 possess a well-organized 1 or well-differentiated nucleus. These 

 organisms are usually minute and spherical, rod-shaped or spiral, 

 in most genera not producing true filaments, and rarely branching. 

 The cells may occur singly, in chains, or other groupings. They 

 may be motile by means of flagella, or non-motile, but they are never 

 notably flexuous. Cell multiplication occurs always by transverse, 

 never by longitudinal, fission. Some genera produce endospores, 

 particularly the rod-shaped types. Conidia are not observed. 

 Chlorophyll is absent, though the cells may be pigmented. The 

 cells may be united into gelatinous masses, but they never form 

 motile pseudoplasmodia nor develop a highly specialized cyst- 

 producing fruiting stage, such as is characteristic of the My.ro- 

 bacteriales. 



FAMILY l.Nitrobacteriacece. Organisms usually rod-shaped 

 (sometimes nearly spherical in Nitrosomonas and possibly in Azoto- 

 bacter). Cells motile or non-motile. Branched involution forms in 

 Rhizobium and Acetobacter. Endospores never formed. Obligate 

 aerobes, capable of securing growth energy by the direct oxidation 

 of carbon, hydrogen, or nitrogen, or of simple compounds of these. 

 Non-parasitic (except in Genus Rhizobium) usually water or earth 

 forms. 



Tribe 1. Nitrobacterece. Organisms deriving their life energy 

 from oxidation of simple compounds of carbon and nitrogen (or of 

 alcohol). 



Genus 1. Hydrogenomonas. Monotrichic short rods capable of 

 growing in the absence of organic matter and securing growth energy 

 by the oxidation of hydrogen (forming water). Kaserer (1905) who 

 first described the organism states that his species will also grow well 

 on a variety of organic substances. Type species, Hydrogenomonas 

 pantetropha (Kaserer 1906) Orla-Jensen. Nikleuski (1910) described 

 two additional species, H. mtrea and H . flava. 



