GENERAL SYSTEMATIC BACTERIOLOGY 31 



b. Cells elongate. 



1. Cells not spiral. 



(a) Cells separating when formed. 



Bacterium 



(b) Cells forming a chain or filament. 



Bacillus 



(c) Filaments relatively long. 



(1) Sheathless Leptothrix 



(2) Sheathed Crenothrix 



(d) Filaments branched Cladothrix 



(e) Enclosed in gelatin Ascobacteria 



(f ) Naked cells Polybacteria 



2. Cells spiral. 



(a) Cells separating quickly.. Fz6no 



(b) Spiral, like a spring Spirillum 



(c) Cells longer and more slender. 



Spirochaete 



(d) Cells embedded in gelatin. 



Myconostoc 

 II. Cell division in two directions of space, giving rise to tetrads. 



Merista 

 III. Cell division in three directions of space forming cubical packets. 



Sarcina 



The genera Streptococcus for the chain cocci and Staphylococcus 

 for the irregularly grouped cocci from pus were first adequately defined 

 by Rosenbach (1884). Both of these names had previously been used 

 by other writers, but Rosenbach was apparently the first to associate 

 them definitely with species. 



Zopf (1884) in the third edition of Die Spaltpilze materially modi- 

 fied and enlarged the bacterial classification used in the first and second 

 editions. The four main groups were recognized as before, but the 

 number of genera increased. Following is the classification used: 



Zopf s Classification of Bacteria (1885) 



a. Cells producing only a spherical stage. 



b. Not embedded in firm masses of gelatin, 

 c. Cells regularly arranged. 



d. Cells in chains Streptococcus 



dd. Cells not in chains. 



e. Cell division in two planes, forming flat plates of 



cells Merismopedia 



ee. Cell division in three planes, forming regular cubes and 



packets Sarcina 



cc. Cells irregularly arranged Micrococcus 



