BOOK VIII.. Philosophy of the Classificatory Sciences.

PHILOSOPHY OF THE CLASSIFICATORY SCIENCES.

CHAP. I. THE IDEA OF LIKENESS AS GOVERNING THE USE OF COMMON NAMES 95

Art. 1. Object of the Chapter. 2. Unity of the Individual. 3. Condition of Unity. 4. Kinds. 5. Not made by Definitions. 6. Condition of the Use of Terms. 7. Terms may have different Uses. 8. Gradation of Kinds. 9. Characters of Kinds. 10. Difficulty of Definitions. 11. 'The Five Words.'

CHAP. II. THE METHODS OF NATURAL HISTORY, AS REGULATED BY THE IDEA OF LIKENESS 108

Sect. I. Natural History in General. Art. 1. Idea of Likeness in Natural History. 2. Condition of its Use.

Sect. II. Terminology. Art. 3. Meaning of the word.

Sect. III. The Plan of the System. Art. 4. Its Meaning. 5. Latent Reference to Natural Affinity. 6. Natural Classes. 7. Artificial Classes. 8. Are Genera Natural? 9. Natural History and Mathematics. 10. Natural Groups given by Type, not by Definition. 11. Physiography. 12. Artificial and Natural Systems. {ix} Sect. IV. Methods of framing Natural Systems. Art. 13. Method of Blind Trial. 14. Method of General Comparison.

Sect. V. Gradation of Groups. Art. 15. Series of Subdivisions. 16. What is a Species? 17. The words 'Species' and 'Genus.' 18. Varieties. Races.

Sect. VI. Nomenclature. Art. 19. Binary Nomenclature.

Sect. VII. Diagnosis. Art. 20. Characteristick and Systematick.

CHAP. III. APPLICATION OF THE NATURAL HISTORY METHOD TO MINERALOGY 138

Art. 1. Mohs's System. 2. His 'Characteristick.' 3. Mineral Species not yet well fixed. 4. Orders of Minerals. 5. Nomenclature of Minerals. 6. M. Necker's 'Règne Mineral.' 7. Inconvenience of taking a Chemical Basis of Mineral Systems. 8. Relation of Natural History and Chemistry. 9. What is a Mineralogical Individual? 10. A well-formed Crystal is an Individual. 11. Not the Integrant Molecules, 12. Nor the Cleavage Forms. 13. Compound Crystals are not Individuals. 14. Crystalline Forms are sufficiently complete for this. 15. Including aggregate Masses. 16. Do Artificial Crystals belong to Mineralogy? 17. The Mineralogical Individual extends as far as the same Crystalline Axes extend. 18. Artificial Crystals do belong to Mineralogy: {x} 19. Cannot be excluded. 20. Species to be determined by the Crystalline Power. 21. Secondary Derivative Forms are Varieties: 22. Are not Species, as M. Necker holds.

CHAP. IV. OF THE IDEA OF NATURAL AFFINITY 159

Art. 1. The Idea of Affinity 2. Is not to be made out by Arbitrary Rules. 3. Functions of Living things are many, 4. But all lead to the same arrangement. 5. This is Cuvier's principle: 6. And Decandolle's. 7. Is this applicable to Inorganic Bodies? 8. Yes; by the agreement of Physical and Chemical Arrangement.