CHAPTER I 



Classification of the Genera and Higher Groups 

 OF Bacteria 



Apparently the first definite named description of any organism in- 

 cluded now among the bacteria is probably that of Mueller in his 

 Vermium terrestrium etfluviatilum (1773). The following key, abridged 

 from his introduction, gives the main groupings and the genera of the 

 group in which the bacteria fall. 



Mueller's Classification of Vermes (1773) 



a. Tentaculi destituti. 



b. Vagantes Infusoria 



c. Organis externis nuUis 

 d. Teretes. 



1. Corpus punctiforme Monas 



2. Corpus sphaericina Volvox 



3. Corpus cylindraceum .... Enchelis 



4. Corpus elongatum Vibrio 



5. Corpus cavum Bursaria 



dd. Complanati. (With four genera.) 



cc. Organis externis. (With four genera.) 



bb. Serpentes Helminthica 



(With eight genera.) 



aa. Tentaculis instruct! Teslacea 



(With twelve genera.) 



Later in the introduction to the above volume the two genera Monas 

 and Vibrio (which contain his bacterial species) are noted as found 

 among the Aquatici, also among the Hyalini, also under Tentaculis 

 nullis, inconspicui, teretes, and still later under Vacillantes, pellucidi. 

 Finally he places these genera with Volvox and Enchelis in a classi- 

 fication imder the headings Organis externis nullis, crassiuscula. 



Three species of Monas are described. The generic description is 

 " Vermis inconspicuus, simplicissimus pellucidus, punctiformus. " The 

 genus Vibrio is described as " Vermis inconspicuus, simplicissimus, 

 teres, elongatus." Fifteen species are described. Several of them were 

 doubtless bacterial forms. 



In the year 1786 there appeared a posthumous volume by Mueller, 

 entitled "Animalcula Infusoria fluviatilia et marina." The infusoria 



15 



