GENERAL MORPHOLOGY AND PHYSIOLOGY 39 



defined groups are recognized: Cladothrix, Crenothrix, Phragmidiothrix, 

 and Thiothrix. 



VII. Family BEGGIATOACE^E. Beggiatoa. Family characters not 

 clearly defined. Motile, though no flagellae have been observed. Beg- 

 giatoa is the most important genus. 



Recently (1917) the Society of American Bacteriologists appointed 

 a committee on bacterial nomenclature with instructions to look into the 

 matter of bacterial classification and to propose a system which would in 

 a way represent the biological and phylogenetic relationships of the prin- 

 ciple groups. The following classification is offered by this committee, 

 hoping that it may serve as the basis for further efforts along this line. 



2. Suggested Outline of Bacterial Classification 

 THE CLASS SCHIZOMYCETES 



Minute, one-celled, chlorophyll-free, colorless, rarely violet-red or 

 green-colored plants, which typically multiply by dividing in one, two or 

 three directions of space, the cells thus formed sometimes remaining united 

 into filamentous, flat, or cubical aggregates. Filamentous species often 

 surrounded by a common sheath. Capsule or sheath composed in the 

 main of protein matter. The cell plasma generally homogeneous without 

 a nucleus. Sexual reproduction absent. In many species resting bodies 

 are produced, either endospores or gonidia. Cells may be motile by means 

 of flagella. 



A. ORDER MyxoBACTERiALES. 1 Cells united during the vegetative 

 stage into a pseudoplasmodium which passes over into a highly-developed 

 cyst-producing resting stage. 



B. ORDER TmoBACTERiALES. 1 Cells free or united in elongated 

 filaments. Water forms, not easily cultivable. 'Life energy derived 

 mainly from oxidative processes. Cells typically containing either gran- 

 ules of free sulphur or bacterio-purpurin, or both, usually growing best 

 in the presence of hydrogen sulphide. 



C. ORDER CnLAMYDOBACTERiALES. 1 Cells normally united in elon- 

 gated filaments. Sulphur and bacterio-purpurin are absent. Iron often 

 present and usually a well-marked sheath. 



D. ORDER EUBACTERIALES. Ordo nov. Synonyms: Bacterina 

 Perty 1^52 in part; Eubacteria Schroeter 1886; Eubacteriaceae A. J. 

 Smith 1902. 



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 



1 These first three orders are included briefly to give the complete setting of the 

 fourth, the Eubaeteriales, with which we are primarily concerned. 



