460 GENERAL SYSTEMATIC BACTERIOLOGY 



The name has frequently been used in the form Schizomyceten, 

 Schizomycetacea (q.v.) and Schizomycetaceae. 



Hansgirg (1888, p. 229) gives this as a synonym of Bacteria. 



Clements (1909, p. 8) recognizes this as a class name with the two 

 orders Bacteriales and Myxohactrales, and the description: 



Typically one-celled fungi, dividing by fission in 1, 2 or 3 planes, sometimes 

 forming true filaments, but then motile or sheathed, and without true branches; 

 resting cells often developed; sexual reproduction lacking. 



Vuillemin (1913, p. 512) gave an excellent characterization of the 

 group. He states that they are simple organisms, formed of a single 

 element without septa and unbranched. The element is circumscribed 

 by a rigid vegetable like membrane, elastic, but not contractile, some- 

 times also with a capsule. It may undergo plasmolysis of plasmoptysis. 

 The protoplasm is less differentiated than that of most cells; the chro- 

 matin particles do not form an individual nucleus of a permanent type. 

 Division is amitotic. Some forms are motile with flagella which traverse 

 the membrane at points characteristic of the species (polar or diffuse). 

 They are not broader than Sju when not in bunches or unimpregnated 

 with metal or colloidal coloring material. The resting stage may be 

 either an arthrospore resulting from a simple modification of the mem- 

 brane or an endospore. In some cases the spore bearing element retains 

 its form or is modified passively by the enlargement of the spore, in other 

 cases it is a specialized element for spore production. Only the latter 

 type of sporulation is satisfactory for generic characters. The amitotic 

 division usually occurs by a pinching transversely with rapid separation 

 of two individuals. These may remain united into families, in chains, 

 layers or packets as determined by the successive planes of division. He 

 emphasizes that all forms showing contractility should be placed in the 

 protozoa, that the myxobacteria constitute a distinct group, and that 

 forms like the tubercle bacillus which show branching should be placed 

 in the mold group Microsiphones. 



Buchanan (1917, p. 155) used the following characterization: 



Typically unicellular plants, cells usually small and relatively primitive in 

 organization. The cells are of many shapes, spherical, cylindrical, spiral or 

 filamentous; cells often united into groups, families or filaments; cccasionally in 

 the latter showing some differentiation among the cells, simulating the organiza- 

 tion seen in some of the blue-green, filamentous algae. No sexual reproduction 

 known. Multiplication typically by cell fission. Endospores are formed by some 

 species of the Euhacteriales (see below), gonidia (conidia, arthrospores) bj' some 

 of the filamentous forms. Chlorophyll is produced by none of the bacteria (with 



