GENERAL SYSTEMATIC BACTERIOLOGY 117 



It is evident that this principle makes possible the recommendation 

 and adoption of special rules to govern groups such as the bacteria. 

 Some such special rules have been suggested to the Society of American 

 Bacteriologists through its committee on bacterial classification. 



Chapter II. On the manner of designating the nature and the sub- 

 ordination of the groups which constitute the plant kingdom 



Article 10. Every individual plant belongs to a species (species), every species 

 to a genus (genus), every genus to a family (familia), every family to an order 

 (ordo), every order to a class (classis), every class to a division (divisio). 



Article 11. In many species we distinguish varieties (varietas) and forms 

 (forma); and in some cultivated species, modifications still more numerous; in 

 many genera sections (sectio), in many families tribes (tribus). 



Article 12. Finally if circumstances require us to distinguish a greater number 

 of intermediate groups, it is easy, by putting the syllable sub before the name of a 

 group, to form subdivisions of that group. In this way subfamily (subfamilia) 

 designates a group between a family and a tribe, subtribe (subtribus) a group be- 

 tween a tribe and a genus, etc. The arrangement of subordinate groups may thus 

 be carried, for wild plants only, to twenty-one degrees, in the following order: 

 Regnum vegetabile, Divisio, Subdivisio, Classis, Subclassis, Ordo, Subordo, 

 Familia, Subfamilia, Tribus, Subtribus, Genus, Subgenus, Sectio, Subsectio, 

 Species, Subspecies, Varietas, Subvarietas, Forma, Individuum. 



If this list of groups is insufficient it can be augmented by the intercalation of 

 supplementary groups, so long as these do not introduce confusion or error. 



Example : Series and Subseries are groups which can be intercalated between 

 subsection and species. 



Recommendation. I. In parasites, particularly in parasitic fungi, authors who 

 do not recognize as species forms which are characterized from a biologic point of 

 view, but little or not at all from the standpoint of morphology may differentiate 

 within species special forms (forma specialis, f. sp.) characterized by their adap- 

 tation to their different hosts. 



Article 13. The definition of each of these names of groups varies, up to a cer- 

 tain point, according to individual opinion and the state of the science, but their 

 relative order, sanctioned by custom must not be altered. No classification is 

 admissible which contains such alterations. 



Examples of inadmissible alterations are — a form divided into varieties, a 

 species containing genera, a genus containing families or tribes. 



Article 14. The fertilization of one species by another gives rise to a hybrid 

 (hybrida), that of a modification or subdivision of a species by another modifica- 

 tion to the same species gives rise to a half-breed (mistus, mule of floristis). 



Chapter III. On the manner of designating each group or associa- 

 tion of plants 



Section 1. General 'principles; priority 



Article 15. Each natural group of plants can bear in science only one valid 

 designation, namely, the oldest, provided that it is in conformity with the rules 

 of Nomenclature and the conditions laid down in articles 19 and 20 of section 2. 



