The proof sheets of this volume, like those of the last volume, have been looked through by Dr. Hooker and Prof. Huxley; and I have, as before, to thank them for their valuable criticisms, and for the trouble they have taken in checking the numerous statements of fact on which the arguments proceed. The consciousness that their many duties render time extremely precious to them, makes me feel how heavy is my obligation.
Part IV., with which this volume commences, contains numerous figures. Nearly one half of them are repetitions, mostly altered in scale and simplified in execution, of figures, or parts of figures, contained in the works of various Botanists and Zoologists. Among the authors whom I have laid under contribution, I may name Berkeley, Carpenter, Cuvier, Green, Harvey, Hooker, Huxley, Milne-Edwards, Ralfs, Smith. The remaining figures, numbering 150, are from original sketches and diagrams.
The successive instalments which compose this volume, were issued to the Subscribers at the following dates:—No. 13 (pp. 1–80) in January, 1865; No. 14 (pp. 81–160) in June, 1865; No. 15 (pp. 161–240) in December, 1865; No. 16 (pp. 241–320) in June, 1866; No. 17 (pp. 321–400) in November, 1866; and No. 18 (pp. 401–566) in March, 1867.
London, March 23rd, 1867.
CONTENTS OF VOL. II.
| PART IV.—MORPHOLOGICAL DEVELOPMENT. | ||
| CHAP. | PAGE | |
|---|---|---|
| I.— | The problems of morphology | [3] |
| II.— | The morphological composition of plants | [17] |
| III.— | The morphological composition of plants—Continued | [37] |
| IV.— | The morphological composition of animals | [85] |
| V.— | The morphological composition of animals—Continued | [111] |
| VI.— | Morphological differentiation in plants | [128] |
| VII.— | The general shapes of plants | [134] |
| VIII.— | The shapes of branches | [145] |
| IX.— | The shapes of leaves | [152] |
| X.— | The shapes of flowers | [161] |
| XI.— | The shapes of vegetal cells | [175] |
| XII.— | Changes of shape otherwise caused | [178] |
| XIII.— | Morphological differentiation in animals | [183] |
| XIV.— | The general shapes of animals | [186] |
| XV.— | The shapes of vertebrate skeletons | [209] |
| XVI.— | The shapes of animal cells | [228] |
| XVII.— | Summary of morphological development | [231] |
| PART V.—PHYSIOLOGICAL DEVELOPMENT. | ||
| I.— | The problems of physiology | [239] |
| II.— | Differentiations between the outer and inner tissues of plants | [244] |
| III.— | Differentiations among the outer tissues of plants | [251] |
| IV.— | Differentiations among the inner tissues of plants | [272] |
| V.— | Physiological integration in Plants | [292] |
| VI.— | Differentiations between the outer and inner tissues of animals | [299] |
| VII.— | Differentiations among the outer tissues of animals | [309] |
| VIII.— | Differentiations among the inner tissues of animals | [323] |
| IX.— | Physiological integration in animals | [373] |
| X.— | Summary of physiological development | [384] |
| XA.— | The integration of the organic world | [396] |
| PART VI.—LAWS OF MULTIPLICATION. | ||
| I.— | The factors | [411] |
| II.— | À PRIORI principle | [417] |
| III.— | Obverse À PRIORI principle | [424] |
| IV.— | Difficulties of inductive verification | [432] |
| V.— | Antagonism between growth and asexual genesis | [439] |
| VI.— | Antagonism between growth and sexual genesis | [448] |
| VII.— | The antagonism between development and genesis, asexual and sexual | [461] |
| VIII.— | Antagonism between expenditure and genesis | [467] |
| IX.— | Coincidence between high nutrition and genesis | [475] |
| X.— | Specialities of these relations | [486] |
| XI.— | Interpretation and qualification | [497] |
| XII.— | Multiplication of the human race | [506] |
| XIII.— | Human population in the future | [522] |
| APPENDICES. | ||
| A.— | Substitution of axial for foliar organs in plants | [541] |
| B.— | A criticism on Prof. Owen’s theory of the vertebrate skeleton | [548] |
| C.— | On circulation and the formation of wood in plants | [567] |
| D.— | On the origin of the vertebrate type | [599] |
| D2.— | The annulose type | [602] |
| E.— | The shapes and arrangements of flowers | [608] |
| F.— | Physiological (or constitutional) units | [612] |
| G.— | The inheritance of functionally-caused modifications | [618] |
PART IV.
MORPHOLOGICAL DEVELOPMENT.
CHAPTER I.
THE PROBLEMS OF MORPHOLOGY.
§ 175. The division of Morphology from Physiology, is one which may be tolerably-well preserved so long as we do not carry our inquiries beyond the empirical generalizations of their respective phenomena; but it is one which becomes in great measure nominal, when the phenomena are to be rationally interpreted. It would be possible, after analyzing our Solar System, to set down certain general truths respecting the sizes and distances of its primary and secondary members, omitting all mention of their motions; and it would be possible to set down certain other general truths respecting their motions, without specifying their dimensions or positions, further than as greater or less, nearer or more remote. But on seeking to account for these general truths, arrived at by induction, we find ourselves obliged to consider simultaneously the relative sizes and places of the masses, and the relative amounts and directions of their motions. Similarly with organisms. Though we may frame sundry comprehensive propositions respecting the arrangements of their organs, considered as so many inert parts; and though we may establish several wide conclusions respecting the separate and combined actions of their organs, without knowing anything definite respecting the forms and positions of these organs; yet we cannot reach such a rationale of the facts as the hypothesis of Evolution aims at, without contemplating structures and functions in their mutual relations. Everywhere structures in great measure determine functions; and everywhere functions are incessantly modifying structures. In Nature the two are inseparable co-operators; and Science can give no true interpretation of Nature without keeping their co-operation constantly in view. An account of organic evolution, in its more special aspects, must be essentially an account of the interactions of structures and functions, as perpetually altered by changes of conditions.
Hence, when treating apart Morphological Development and Physiological Development, all we can do is to direct our attention mainly to the one or to the other, as the case may be. In dealing with the facts of structure, we must consider the facts of function only in such general way as is needful to explain the facts of structure; and conversely when dealing with the facts of function.