412 GENERAL SYSTEMATIC BACTERIOLOGY 



Paraschizae. A subdivision of the group Schizomycetes named by 

 Jennings (1899, p. 315) to include the genera Astrohader and Pasteuria 

 characterized by longitudinal rather than transverse fission of the 

 cell in multipHcation. The coordinate subdivision is named Diaschizae. 



Paraspirillum. A genus used by Dobell (1911, p. 97) to include 

 the species Paraspirillum vejdovskii found in a culture of Oscillatoria. 



The living organisms are, for the most part, in the form of spiral or S-shaped 

 rods, very like ordinary spirilla. Short individuals are about 8/n in length, the 

 largest individuals attaining a length of about 25iu. The average length is about 

 15fi. 



The organisms are variable in thickness, with a well marked thicken- 

 ing toward the middle of the body. They taper decidedly toward the 

 ends. The cell is described as a "much elongated and spirally twisted 

 spindle." "In the middle region, the organisms measure from 1.5;u to 

 2ji across^ — the thickness varying in different individuals." 



In each living cell at thickest point is an oval or rounded structure 

 regarded as a nucleus. Immediately surrounding the nucleus is an 

 area of hyaline cytoplasm. Toward the ends of the cells are granular 

 inclusions (volutin or metachromatic granules). 



"Movement from place to place is effected by means of flagella, 

 similar to those of common spirilla. In the living organisms, I have 

 never succeeded in seeing any flagella." The flagella were demon- 

 strated, however, in stained mounts, a single one, or one at each end. 



The genus was recognized as the third of the family Spirillaceae by 

 Buchanan (1918, p. 179) with the description: 



Cells spiral or S-shaped, like spirilla, variable in thickness, with a well marked 

 thickening toward middle of the body, and tapering toward the ends, a much 

 elongated and spirally twisted spindle. Motile by means of flagella. 



The type species is Paraspirillum vejdovskii Dobell. 



Pasteurella. A genus created by Trevisan (1887, p. 94) primarily 

 to include the bacillus of fowl cholera. His description follows: 



Pasteurella, Trevis. (nuovo genere). Tre stadi di sviluppo vegetativo: 1. 

 Baculi, 2. Filamenti, 3. Cocchi. Baculi (stadio primigeno tipico) brevemente 

 cilindrici o ellissoidi, inarticolati incolori; protoplasma polare-diblastico. Fila- 

 menti (stadio anormale transitorio) visulanti da baculi rimasti in conguinzione 

 per incompleta temnogenesi. Cocchi segregati (monococchi e cocchi ottoformi) 

 o seriati in catenelle. Spore provenienti nei baculi. 



The species first named is Pasteurella cholerae-galUnarum. Other 

 species named were P. Davainei and P. suilla. Later (1889, p. 21) 



