28 MISCELLANEOUS PUBLICATION 9 55, U.S. DEPT. OF AGRICULTURE 



menclature deals with names. In microbiology it deals chiefly with 

 the names of micro-organisms and groups of micro-organisms. Tax- 

 onomy is the science of classification. Microbial taxonomy pertains 

 to the relationships among micro-organisms and their groups. 



Such common names of micro-organisms as viruses, rickettsiae, bac- 

 teria, actinomycetes, algae, protozoa, and fungi are used by English- 

 speaking people. Those who speak other languages use equivalent 

 although often quite different names. A scientific nameis properly 

 derived from either Latin or Greek or else is Latinized; i.e., made to 

 conform to Latin rules. It is used without change by scientists all 

 over the world, except for possible transliteration to Russian, Hindi, 

 Chinese, and other languages with different systems of writing. 



Often scientific names are so constructed as to describe a distinctive 

 characteristic of the micro-organism. For example, the scientific name 

 for bacteria is Schizomycetes, which means literally fission fungi, a 

 reference to their mode of reproduction. However, a name is funda- 

 mentally a device and need not be at all descriptive. Names have been 

 derived from those of famous men and women, mythical characters, 

 and cities and rivers. Salmonella is a genus of bacteria named to 

 commemorate D. E. Salmon, an American bacteriologist. Proteus 

 is a generic name, which is also the name of a Greek polymorphic 

 sea god. Nevskia, derived from the Neva River in Russia, is also a ■ 

 generic name. 



Names of micro-organisms, like those of larger forms of life, al- 

 ways appear in two parts, e.g., Hansenula anomala. The first part 

 is the genus name and is equivalent to the surname of a person. It is 

 always capitalized. The second part is the species name and might be 

 likened to our Christian names. Generally the species name is not 

 capitalized. In keeping with the convention that foreign words and 

 phrases are often written in italics, genus and species names are 

 italicized or in some other way made to stand out from the rest of a 

 printed passage. 



Names are also applied to ranks below species and above genus in 

 the taxonomical hierarchy. To indicate a variety the abbreviation 

 "var." should be placed after the species named and then the varietal 

 name is appended, e.g., Bacillus subtitlis var. niger. Sometimes the 

 word or abbreviation for the subspecific rank is omitted, e.g., Bacillus 

 cereus mycoides. This method of designating subspecific forms is not 

 recommended, because the resulting name resembles an illegal trino- 

 mial and the rank is not specified. 



Higher ranks, such as family, order, and class, are also given Latin 

 or Latinized names. At these taxonomic levels the rules of nomen- 

 clature differ according to which code is followed. For proper end- 

 ings and other information, one should consult whichever of the 

 following references is appropriate: International Code of Nomen- 

 clature of Bacteria and Viruses (17), International Code of Botanical 

 Nomenclature (16), and International Rules of Zoological Nomen- 

 clature (26). 



Theoretically each micro-organism has one name that takes 

 precedence over all others applied to it. Because no one system of 

 classification has gained universal acceptance, micro-organisms often 

 have several names. Microbiologists of one country commonly adhere 



