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which vegetables are constructed, or to the external appearance their elementary organs assume in a state of combination. It is exceedingly desirable that these topics should be well understood, because they form the basis of all other parts of the science. In physiology, every function is executed through the agency of the organs : systematic arrangements depend upon characters arising out of their consideration ; and descriptive Botany can have no logical precision until the principles of Organography are exactly settled. A difference of opinion exists among the most distinguished botanists, upon some points connected with this subject, so that it has been found expedient to enter occasionally into much detail, for the purpose of satisfying the student of the accuracy of the facts and reasonings upon which he is expected to rely.

To this succeeds VEGETABLE PHYSIOLOGY (Book II.); or the History of the vital phenomena that have been observed both in plants in general, and in particular species, and also in each of their organs taken separately. It is that part of the science which has the most direct bearing upon practical objects. Its laws, however, are either unintelligible, or susceptible of no exact appreciation, without a previous acquaintance with the more important details of Organography. Much of the subject is at present involved in doubt, and the accuracy of some of the conclusions of physiologists is inferred rather than demonstrated; so that it has been found essential that the grounds of the more popularly received opinions, whether admitted as true or rejected as erroneous, should be given at length.

Next follows Glossology (Book III.); or, as it was formerly called, TERMINOLOGY; restricted

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to the definition of the adjective terms, which are either used exclusively in Botany, or which are employed in that science in some particular and unusual sense. The key to this book, and also to the substantive terms explained in Organography, will be found in a copious index at the end of the volume.

These topics exhaust the science considered only with reference to first principles; there is, however, another which it has been thought advisable to append, on account of its practical value, namely PHYTOGRAPHY (Book IV.); or, an exposition of the rules to be observed in describing and naming plants. As the great object of descriptions in natural history, is to enable every person to recognise a known species, after its station has been discovered by classification, and also to put those who have not had the opportunity of examining a plant themselves into possession of all the facts necessary to acquire a just notion of its structure and affinities; it is indispensable that the principles of making descriptions should be clearly understood, both to prevent their being too general to answer the intended purpose, or more prolix than is really requisite. It is the want of a knowledge of these rules that renders the short descriptions of the classical writers of antiquity, and the longer ones of many a modern traveller, equally vague and unintelligible. In this place are inserted a few notes upon the formation of an herbarium.

It has been my wish to bring every subject that I have introduced down, as nearly as possible, to the state in which it is found at the present day. In doing so, I have added so very considerable a quantity of new matter, especially in what relates to

Vegetable Anatomy and Physiology, that the present edition may be considered, in those respects, a new work.

In the statements I have made, it has been my wish to render due credit to all persons for the discoveries by which they may severally have contributed to the advancement of the science; and if I have on any occasion either omitted to do so, or assumed to myself observations which belong to others, it has been unknowingly or inadvertently. It is, however, impracticable, and if practicable it would not be worth while, to remember upon all occasions from what particular sources information may have been derived. Discoveries, when once communicated to the world, become public property: they are thrown into the common stock for mutual benefit; and it is only in the case of debatable opinions,

any recent and unconfirmed observations, that it really interests the world that authorities should be quoted at all. In the language

In the language of a highly valued friend, when writing upon another subject, — “ The advanced state of a science is but the accumulation of the discoveries and inventions of many: to refer each of these to its author is the business of the history of science, but does not belong to a work which professes merely to give an account of the science as it is : all that is generally acknowledged must pass current from author to author.” *

or

London, May, 1839.

* Brett's Principles of Astronomy, p. v.

CONTENTS.

-

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Absolute Terms

445
of Figure

446
of Outline

455
of Apex

458
of Marginal Division 460
of Incision
of Composition

463
of Marking or Even-
ness

467
of Superficial Append-
ages

468
of Polish or Surface 471
of Texture or Substance 471
of Size

473
of Duration

. 475
of Colour
of Variegation

481
of Veining

482
Relative Terms

483
Estivation

483

Direction

485

Insertion

489
Collective Terms

491

Arrangement • 491

Number

495

Qualifying Terms

496

Signs

496

Abbreviations

499

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BOOK II.

PHYSIOLOGY.

- 358

- 360

General Considerations

277

Chap. I. Chemical Constitution

of Elementary Organs 289

Chap. II. Elementary Organs 296

Chap. III. Symmetry

302

CHAP. IV. Root

304

Chap. V. Stem and Origin of

Wood

309

Chap. VI. Leaves

324

Chap. VII. Bracts

330

Calyx and Corolla

330

Disengagement of Caloric 333

CHAP. VIII. Fertilisation 337

Sexuality of Plants denied 345

Mules

948

Chap. IX. Fruit

351

Changes during ripening 354

Bletting

356

Chap. X. Seeds

958

Their Longevity

Germination

359. 363

Respiration

Action of Heat

S61

Chap. XI. Food of Plants 366

Carbon

366

Water

367

Nitrogen

- 368

Power of Solution

- 369

Exhaustion of Soil

Manures

371

Chap. XII. Digestion

372

Decomposition of Carbonic

Acid

Fungi

378

Hydrogen

379

Nitrogen

979

Foreign Matter

- 380

Light

382

Excretions

383

Nitrogen

385

Hydrogen

385

Sulphurous Acid Gas

- 385

Muriatic Acid Gas

- 386

Chlorine

386

Nitrous Acid Gas

386

Sulphuretted Hydrogen 386

Ammonia

387

Cyanogen

387

Carbonic Oxide

387

Olefiant Gas

388

Protoxide of Nitrogen

- 388

- 370

- 373

BOOK IV. - PHYTOGRAPHY.

Chap. I. Diagnoses

507

Differential Characters · 508

Essential Characters

508

Chap. II. Descriptions

514

Chap. III. Punctuation

526

CHAP. IV. Nomenclature

528

Terminology

532

Chap. V. Synonyms

534

Chap. VI. Herbaria

537

Chap. VII. Botanical Drawings 544

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