Classification of the Schizomycetes. 69 



coccus may become a Bacterium, a Bacterium a Bacillus, a 

 Leptothrix, or even a Spirillum and a Spirochaeta. Ray 

 Lankester (Quart. Jour. Micr. Sri., xiii., 1873, P- 4^) 

 and Lister were the first to promulgate this opinion in 

 England; but the truth of the former's observations, on 

 Bacterium rubescens, has been partially denied by several 

 observers, and is not yet entirely free from doubt. 



The first classification of the Schizomycetes was that 

 due to Ehrenberg, in 1838 (" Die Infusionsthierchen," 

 P- 7S) f which the following is the essential part : 



u. fig" 1 - " ' Bacterium 



Cells straight { snake . like> flexi i e ......... Vibrio 



< flexile ... Spirochate 



Cells spiral j rigid ...... 



It may be noted that Vibrio is here conceived to be 

 naturally straight-lined, but capable of bending in undula- 

 tions of a serpentine form, being thus distinguished from 

 Spirillum by the fact that the undulations lie all in one plane. 

 But most modern observers are agreed that the species 

 referred to Vibrio belong to two classes the one, in which 

 the undulations are serpentine, being merely Bacillus ; the 

 other, in which they are spiral, being undistinguishable from 

 Spirillum. This is, therefore, another reason, added to those 

 which Dr. Winter has given (supra, p. 46), why the name 

 Vibrio should be dropped. 



Cohn's first classification (1872) is merely a modification 

 of Ehrenberg' s. 



A. Cells at times united in gelatinous families. 



a. Cells round, Sphserobacteria ... ... Micrococcus 



b. Cells oblong, Microbacteria ... ... ... Bacterium 



B. Cells never united in gelatinous families. 



a. Cells thread-like, Desmobacteria. 



1. Threads straight ... ... ... Bacillus 



2. Threads undulated -... Vibrio 



