BACTERIA. 41 



posing animal and vegetable matters, or as parasites 

 upon the tissues or juices of living animals or plants. 

 This lowest family, the fungi, are divisible into the 



Hyphomycetes or Mucorini, or moulds; 

 Saccharomycetes, or yeasts; and 

 Schizomycetes, or bacteria. 



Cohn divided the bacteria, according to their mor- 

 phology, into 



Sphero-bacteria, or cocci ; 

 Micro-bacteria short rods ; 

 Desmo-bacteria bacilli ; 

 Spiro-bacteria spirilla-. 



Davaine suggested a classification based upon motility, 

 making four classes Bacterium, Vibrio, Bacteridium, 

 and Spirillum, neglecting to provide for the cocci. 



Zopf arranged them, according to his theory of 

 pleomorphism, into the CocCACE^E, comprising those 

 known only in the coccus form, and comprehending 

 the streptococci, merismopedia, sarcina, micrococcus, and 

 ascococcus ; the BACTERIACE^, comprehending the genera 

 bacterium, spirillum, vibrio, leuconostoc, bacillus, and 

 clostridium (chiefly coccus, rod, and thread forms ; the 

 former may be absent ; in the latter there is no distinction 

 between base and apex ; threads straight or screw-like) ; 

 and the LEPTOTHRICHE.^, comprehending crenothrix, 

 beggiatoa, phragmidiothrix, and leptothrix (coccus, rod, 

 and thread forms ; the latter show a distinction between 

 base and apex ; threads straight or screw-like ; spore- 

 formation not demonstrated). 



This classification is, however, based upon what is 

 probably an erroneous principle, the pleomorphism of 

 the bacteria. 



Van Tieghem, DeBary, and Hiippe formed classifica- 

 tions the main feature of which was the formation of 

 endospores or arthrospores, but, as the sporulation of 

 many species is as yet unknown, they cannot be properly 

 placed in it. 



