Page:Bergey's manual of determinative bacteriology.djvu/37

 Prof. R. E. Buchanan

A manual of determinative bacteriology, such as the present volume, has several important functions. These should be recognized and understood by the student if he is to use the volume with satisfaction.

First, the manual should list and describe all the kinds (species) of bacteria and viruses known through adequate publication in bacteriology or virology. Obviously, however, only those organisms that have usable published descriptions can be included.

Second, the manual should arrange the descriptions of the kinds (species) in smaller or larger groups (taxa, singular, taxon) on the basis of resemblances and differences in an effort to show inter-relationships.

Third, the manual should indicate for each species its correct name, likewise the correct name for each group (taxon) of related species.

That branch of biology which has for its purpose the orderly arrangement of the descriptions of species and other taxa, together with the application of the correct names, is termed taxonomy.

The manual, through its indices, should enable the student who knows the correct name of an organism (or even a synonym of such name) to discover the description of the organism and its characteristics, as well as something of its relationships. If, on the other hand, he has an organism whose characteristics and description he has determined or recorded, but whose name and relationships he does not know, a satisfactory manual, through its keys, should enable him to determine the correct name, its probable relationships and its position in a classification.

Nomenclature. The necessity for applying names to species or kinds of bacteria and to groups of inter-related organisms is self-evident. A name given by one person should be understood by others, and as far as practicable all individuals should use the same name for the same kind of organism. It is helpful, therefore, if there can be agreement regarding the method of naming bacteria and agreement as to the correct name for each kind or species. Nomenclature includes all discussions as to methods of naming and of the correctness of particular names.

What kinds of names are used. Two kinds of names are commonly given to the different species of plants and animals, (1) the common, provincial, vernacular or casual names and (2), the international or scientificnames. These should be carefully differentiated, and their respective advantages and disadvantages noted.

It is inevitable, and on the whole probably desirable, that for each kind of