XCV.
The attempts at Natural Classification are of three sorts; according as they are made by the process of blind trial, of general comparison, or of subordination of characters. The process of Blind Trial professes to make its classes by attention to all the characters, but without proceeding methodically. The process of General Comparison professes to enumerate all the characters, and forms its classes by the majority. Neither of these methods can really be carried into effect. The method of Subordination of Characters considers some characters as more important than others; and this method gives more consistent results than the others. This method, however, does not depend upon the Idea of Likeness only, but introduces the Idea of Organization or Function. (viii. 2.)
XCVI.
A Species is a collection of individuals, which are descended from a common stock, or which resemble such a collection as much as these resemble each other: the resemblance being opposed to a definite difference. (viii. 2.) 23
XCVII.
A Genus is a collection of species which resemble each other more than they resemble other species: the resemblance being opposed to a definite difference. (viii. 2.)
XCVIII.
The Nomenclature of a Classificatory Science is the collection of the names of the Species, Genera, and other divisions. The binary nomenclature, which denotes a species by the generic and specific name, is now commonly adopted in Natural History. (viii. 2.)
XCIX.
The Diagnosis, or Scheme of the Characters, comes, in the order of philosophy, after the Classification. The characters do not make the classes, they only enable us to recognize them. The Diagnosis is an Artificial Key to a Natural System. (viii. 2.)