GENERAL SYSTEMATIC BACTERIOLOGY 175 



Winogradsky's three species are recognized. 



An adequate study of this group since the monograph of Winogradsky 

 does not seem to have been made, although the genus Amoebobader 

 Winogradsky has been accepted by many subsequent authors. This 

 genus was included by Migula (1900, p. 1045) in the subfamily Amoebo- 

 baderiaceae, together with the genera Thiodidyon, Thiothece and Thio- 

 polycoccus. IVIigula (1904, p. 146) gave the following generic diagnosis: 

 "Zellen zu Famihen vereinigt, nach einen Richtung des Raumes sich 

 teilend; Familien amoeboid bewegUch, Zellen durch Plasmafaden 

 verbunden. " 



Erwin F. Smith (1905, p. 163) hkewise places the genus in the family 

 Amoebobaderiaceae, and with the following description: 



Cells connected by plasma threads. Families amoeboid motile. The cell 

 families slowly change form, the cells drawing together into a heap or spreading 

 out widely, thus bringing about a change in the shape of the whole family. In 

 a resting condition a common gelatin is extruded, the surface of which becomes 

 a firm membrane. 



In several descriptions, the connecting threads are designated as 

 protoplasmic, apparently without sufficient justification. For example, 

 Frost (1911, p. 61) in a tabulation of Migula's classification states: 



The cells are united into colonies, and after division in one direction of space 

 remain attached together by threads of protoplasm. The colonies possess 

 amoeboid motility. The cells change form by contraction and the spreading out 

 of the protoplasm. 



Buchanan (1918, p. 469) designated the first species described by 

 Winogradsky, A moe6o6ader roseus, as the type. His description follows : 



Cells connected by plasma threads. Families amoeboid motile. The cell 

 families slowly change form, the cells drawing together into a heap or spread- 

 ing out widely, thus bringing about a change in the shape of the whole family. 

 In a resting condition a common gelatin is extruded, the surface becomes a 

 firm membrane. 



Enlows (1920, p. 14) gives the following characterization: 



Cells divide in one direction of space, usuallj' round, and united into families 

 by means of plasma threads. Families have amoeboid motion. In the resting 

 state the extruded gelatin becomes stiffened, forming a firm 2-layered mem- 

 brane. Sulfur granules here and there. Cell masses a delicate rose red. 



Type species (subsequent designation by Buchanan (J. Bact., v. 3, no. 5, 

 1918, p. 469)). Amoebobacter roseus Winogradsky. Cells spherical, 2.8 to 3.4/i 

 in diameter. Winogradsky also includes here A. bacillosus (rodlike cells 2 to 



