!.?;':'iiiK,M ' '':;iH(Kiii»iMs;'.'

lilllll

SYSTEM OF OPHTHALMOLOGY

The scheme for the "System of Ophthalmology" is as follows, but its

division into different volumes is liable to alteration.

Vol. I. THE EYE IN EVOLUTION

Vol. II. THE ANATOMY OF THE VISUAL SYSTEM

Vol. III. NORMAL AND ABNORMAL DEVELOPMENTPt. I. EmbryologyPt. II. Congenital Deformities

Vol. IV. THE PHYSIOLOGY OF THE EYE AND OF VISION

Vol. V. OPHTHALMIC OPTICS AND REFRACTION

Vol. VI. OCULAR MOTILITY AND STRABISMUS

Vol. VII. THE FOUNDATIONS OF OPHTHALMOLOGYHeredity, Pathology, Methods of Diagnosis,General Therapeutics

Vol. VIII. DISEASES OF THE OUTER EYEPt. I. Conjunctiva

Pt. II. Cornea and Sclera

Vol. IX. DISEASES OF THE UVEAL TRACT

Vol. X. DISEASES OF THE RETINA

Vol. XL DISEASES OF THE LENS AND VITREOUS;GLAUCOMA AND HYPOTONY

Vol. XII. NEURO-OPHTHALMOLOGY

Vol. XIII. THE OCULAR ADNEXAnLids, Lacrimal Apparatus, Orbit and Para-orbital Structures

Vol. XIV. INJURIES

Vol. XV. INDEX OF GENERAL AND SYSTEMICOPHTHALMOLOGY

SYSTEM OF OPHTHALMOLOGYEDITED BY

SIR STEWART DUKE-ELDERG.C.V.O., M.A., LL.D., Ph.D., D.Sc, M.D., D.M., F.R.C.S., F.R.C.S.E., F.A.C.S., F.R.A.C.S.

VOL. I

THE EYE IN EVOLUTIONBY

SIR STEWART DUKE-ELDER

WITH 902 ILLUSTRATIONS, 15 COLOURED PLATESAXD 3.')0 MARGINAL ILLUSTRATIONS

ST. LOUIS

THE C. V. MOSBY COMPANY1958

@1958 by Henry Kimpton Publishers,7 Leighton Place,

Leighton Road,

London NWH

All rights reserved. No part of this publication maybe reproduced, stored in a retrieval system, or trans-

mitted, in any form or by any means, electronic,

mechanical, photocopying, recording or otherwise,

without the prior permission of the publishers.

Reprinted 1970, 1976

ISBN 85313 213 a

MADE AND PRINTED IN GREAT BRITAIN

PREFACEThe reception accorded to my Textbook of Ophthalmology has per-

suaded me that there is a need for its continuation in a second edition. Theseven volumes of the Textbook took almost a quarter of a century to write,

a period unfortunately longer than it might have been owing to the exigencies

of war. The first four volumes have long been out of print—and inten-tionally so because they have long been out of date. It is to be rememberedthat the second volume was written before the suljjhonamides were intro-duced ; the third before the antibiotics revolutionized the therapeutics of

infective diseases ; both of them before the role of viruses in ocular diseasewas adequately appreciated ; the physiology of the eye of yesterday isunrecognizable when compared with that of today ; even the anatomy hasbeen transformed by more elaborate optical and chemical methods ofinvestigation and the advent of the electron microscope. The re-writing ofthe whole work if its com^^rehensive nature were to be retained would be animmense task occupying more time than I could reasonably expect to haveat my disposal. Moreover, tomorrow ^^•ill be different from today, and ifa work such as this is to be of any lasting value it would seem to me desirablethat a new edition be published at least every fifteen or twenty years

;

fortunately, ophthalmology is no static science.

It therefore seemed to me wise to sliare the task of re-writing theoriginal Textbook with my colleagues at the Institute of Ophthalmology inLondon. I am grateful that they have accepted this burden. For thisreason I have changed the name of the book to a ''System of Ophthalmology "

since it will necessarih^ be less personal.

This first volume in the new series is an extension of the first twentypages of Volume I of the old Textbook ; this I have %^Titten myself, largelybecause it is a subject in which I am particularly interested—and I wishedto write it. The subject-matter has never been gathered together in a singlebook before and it is my hope that it will interest ophthalmologists in sofar as it forms the basis of the science of vision ; and it may be that it will beof value also to those whose interest is biological rather than clinical.

;

The numerous marginal sketches are not usual in a book of this type.To the student of natural history they may seem superfluous, but to theophthalmologist some of the animals may be unfamiliar and the drawingsmay perchance add meaning to the zoological nomenclature and thus givethe text more life and interest. It is to be noted, however, that they aredrawn not to scale, but approximately to a standard size to fit into a 1-inchmargin,

Stewart Duke-Elder.Institute of Ophthalmology,London,1957.

ACKNOWLEDGEMENTSIn the preparation of this book I have incurred a considerable amount of

indebtedness which is a pleasure to record.Many of the illustrations are borrowed, and in each the source is acknowledged.

There are, however, five sovirces from which I have liberally drawn, and these meritspecial thanks : Dr. Gordon Walls, for a number of his original drawings ; Masson etCie of Paris, who have allowed me to use some illustrations from Rochon-Duvigneaud'sclassical work, Les Yeux et la Vision des Vertebris ; Dr. Maurice Burton and hispublishers, the Elsevier Publishing Co. of Holland, for some illustrations from TheStory of Animal Life ; the Royal Society for permission to iise a large number ofLindsay Johnson's illustrations published in their Proceedings ; and Macmillan & Co.for giving free permission to copy a large number of the illustrations of animals in theCambridge Natural History in the form of inarginal sketches.

In preparing the illustrations I have had the willing co-operation of Dr. PeterHansen and the Department of Medical Illustration of the Institute of Ophthalmology,the assistance of which, particularly that of Mr. T. R. Tarrant, the Medical Artist, hasbeen invaluable. The Zoological Society of London has lent me a number of photo-graphs, as also has the Natural History Museum of London, together with specimensof various invertebrates. Professor Ida Mann has allowed me to use a large numberof her illustrations of the eyes of animals, and Dr. Kevin O'Day of Melbourne hasallowed me to use photographs and slides of the eyes of Monotremes and Marsupialswhich are unobtainable outside Australia ; while in this Institute Professor NormanAshton and Dr. Katharine Tansley have provided me with sections and photographsof the eyes of a number of animals.

In several instances my knowledge of zoology has been brought up to dateby the great kindness of Dr. Mary Whitear of the Zoology Department of UniversityCollege, London, who has read the proofs of those sections dealing with zoologicalclassification ; while Dr. Katharine Tansley and Dr. Robert Weale of this Institutehave given me most helpful criticism in some aspects of the visual problems discussed.Miss M. H. T. Yuille, Mr. A. J. B. Goldsmith and my wife have shared with me theonerous task of proof-reading.

It is difficult for me to express my indebtedness to my secretary. Miss RosamundSoley, who has borne much of the burden of the technical aspects of the production ofthis Volume. She has typed and iDrejDared the manuscript, corrected the proofs, andundertaken the immense and somewhat thankless task of verifying the bibliographies,prepared the Zoological Glossary and the Index, and drawn the 350 marginal sketches.

Finally, my indebtedness to my publishei's, Henry Kimpton, continues to beimmense. They have assisted me in every possible way. Why Mr. G. E. Deed con-tinues to put up with my inoods and vagaries after thirty years is to me quiteincomprehensible.

Stewart Duke -Elder.

CONTENTS

VOLUME I

THE EYE IN EVOLUTION

Part I. The Effect of Light on Living Organisms

Chapter I

Introduction

The Scope of the Subject

The Responses of Organisms to Light Photosynthesis

Chapter II

The Effect of Light on Metabolism : Photoperiodism

MetaboHc Effects of Light .Photoperiodism in Plants

Photoperiodism in Animals .(a) Metabolic Activities .

(b) Sexual Cycle of Animals(c) Pigment Migration .(d) Bioluminescence

(e) Time-memory of Insects and Birds

7

9

13

13

16

19

21

22

Chapter III

The Effect of Light on Movement

Historical DevelopmentTypes of Motorial Responses

(a) Photokinesis

(i) Orthokinesis

(ii) Klinokinesis

(b) Phototropism .(c) Phototaxis

(i)

(ii)

(iii)

(iv)

(V)

(vi)

Klinotaxis

Tropotaxis

Telotaxis

Scototaxis

Menotaxis

Light-compass Reaction, 61 ; Navigational Sense in Birds,

63 ; Orientation to Polarized Light, 66 ; Orientation of

Insects Out-of-doors, 67 ; Orientation to a Visual Pat-tern, 73 ; Dorsal (Ventral) Light Reaction, 74

Mnemotaxis .........

27

31

33

34

34

38

42

47

52

55

60

60

78

CONTENTS

Chapter IV

The Effect of Light on Pigmentation

The Types of Colour ChangeMechanism of Colour Changes

Chromatophores .Types of PigmentTypes of Response

Primary, 89 ; Secondary, 91 ; Indirect, 92

Central Organization of Pigmentary Changes, Nervous and Hormonal

Chapter VThe Emergence of Vision

Light-sensitiveness, the Light Sense and Vision ....

PAGE

82

85

85

87

89

92

102

Part II. The Evolution o! the Visual Apparatus

Chapter VI

The Morphology of Invertebrate Eyes

I. The Genesis of the Eye ....Dermal Photosensitivity.Specific Light-sensitive Cells .

Pigments .....Melanin, 118 ; Visual Pigments, 118 Ommochromes, 122

II. The Structure of Invertebrate Eyes1. Eye-spots : Stigmata

2. Light-sensitive Cells .

3. The Simple Eye(a) The Unicellular Eye .(6) The Multicellular Simple Eye

(i) The Subepithelial Eye(ii) The Epithelial Invaginated Eye

The Flat Eye, 136; the Cupulate Eye, 137; theVesicular Eye, 141

(iii) The Inverted Retina(c) Aggregate Eyes .....(d) Composite Ocelli .....

4. The Compound Eye ......(a) The Development of Ocelli and Compound Eyes(6) The Structure of the Compound Eye .

The Simple Ommatidial Eye, 159 ; the Composite Compound Eye, 160

(i) The Compound Eyes of Arachnids(ii) The Compound Eyes of Crustaceans

(iii) The Compound Eyes of Insects(c) The Optical System of the Compound Eye

The Appositional Eye, 173 ; the Superpositional Eye,174 ; the Analysis of Polarized Light, 174

113

114

115

117

126

125

127

129

130

132

132

135

146

151

152

154

156

157

160

163

166

170

CONTENTS XI

Chapteb VII

The Systematic Anatomy of Invertebrate Eyes

The Structural Variability of Invertebrate Eyes

I. Protozoa ....II. Parazoa (Porifera : Sponges)

III. Invertebrate Metazoa .1. Coelenterata

(a) Cnidaria .

Hydrozoa ; Scyphozoa ; Anthozoa(b) Acnidaria : Ctenophora

2. Echinodermata .....Holothuroidea, 184 ; Echinoidea, 185 ; Asteroidea, 185

3. Worms ....(a) Unsegmented Worms

(i) Platyhelminthes

Turbellaria, 188 ; Trematoda, 189 ; Cestoda, 189

(ii) Nemertea(iii) Nematoda

(6) Segmented Worms : Annelida(i) Oligochpeta .

(ii) Polycheeta

(iii) Archiannelida

(iv) Hirudinea : Leeches

4. Chgetognatha : Arrow-worms6. Rotifera .

6. Polyzoa : Bryozoa

7. Brachiopoda : Lamp Shells8. Mollusca ...

(a) Placophora

(b) Solenogastres .

(c) Seaphopoda

(d) Gastropoda

(e) Lamellibranchiata

(/) Cephalopoda

9. Arthropoda

(a) Onychophora .Crustacea

.

MyriapodaArachnida

Scorpionidea, 211 ; Xiphosura, 212 ; Araneida, 213

Pseudoscorpionidea, 214 ; Pedipalpi, 214 ; Phalangida

215 ; Solifugae, 216 ; Acarina, 216 ; Pycnogonida, 21'

Insecta .......(i) The Stemmata of Larval or Pupal Forms

(ii) The Dorsal Ocelli of Adults .(iii) The Compound Eyes of Adults

(b)

(c)

(d)

{e)

PAGE

178

180

181

181

181

182

182

182

183

186

187

188

189

190

190

190

191

193

193

194

194

194

195

195

196

197

197

197

200

201

204

204

206

210

211

217

222

224

224

Chapter VIII

The Eyes of Proto-chordates

1. Hemichordata .......2. Tunicata : Urochordata......3. Cephalochordata : Lancelots .....

227

228

228

Xll CONTENTS

Chapter IX

The Evolution of the Vertebrate Eye

The Vertebrate Phylum .....1

.

The Phylogeny of the Vertebrate Eye2. The Ontogeny of the Vertebrate Eye3. The Emergence of the Vertebrate Eye4. The General Structm-e of the Vertebrate Eye

PAGE

233

237

239

242

248

Chapter XThe Eyes of Cyclostomes

The Class of Cyclostomes1. The Ammoccete Eye

Light-sensitive Cells

2. The Lamprey Eye .

259

261

263

263

Chapter XI

The Eyes of Fishes

General Configviration of the Eye

.

The Class of FishesL The Selachian Eye .2. The Holocephalian Eye3. The Teleostean Eye4. The Dipnoan Eye5. The Coelacanth Eye6. The Chondrostean Eye7. The Holostean EyeAnomalies in the Eyes of Fishes

(a) The Tubular (Telescopic) Eye

(6) The Amphibious Eye(c) Stalked Eyes .(d) The Migratory Eye .

273

278

279

290

291

312

314

315

321

322

322

324

326

328

Chapter XII

The Eyes of Amphibians

The Class of AmphibiansGeneral Configuration of the Eye.

1. The Anuran Eye2. The Urodelan Eye .

333

334

334

346

Chapter XIII

The Eyes of Reptiles

The Class of Reptiles .General Configuration of the Eye

1. The Lacertilian Eye2. The Chelonian Eye .3. The Crocodilian Eye4. The Rhynchocephalian Eye5. The Ophidian V.ye .

353

353

355

368

375

379

383

CONTENTS Xlll

Chapter XIV

The Eyes of Birds

The Class of BirdsGeneral Configuration of the Eye.

The Avian Eye

397

401

401

Chapter XVThe Eyes of ]\Iam>iaxs

The Class of Mammals1. The Monotreme Eye2. The Marsupial Eye .

The Sub-class of Placentals3. The Placental Eye .

Aquatic Adaptations

429

431

437

441

446

501

Chapter XVI

The Central Organization of Vision

General Principles

II.

The Nervous Control1. The Nerve-net2. Trunk-pathways3. The Ganglionic Nervous System

(a) The Nervous System of Worms(6) The Nervous System of Arthropods

.

(c) The Nervous System of Molluscs4. The Central Nervous System of Vertebrates

Hind-brain, 533 ; Mid-brain, 534 ; Diencephalon, 537

mus, 538 ; Telencephalon, 542

Evolution of the Visual Pathways and Centres

The Hormonal Control ......Hormones and Neuro -secretory Cells

(a) The Neuro-endocrme System of Crustaceans(b) The Neuro -endocrine System of Insects(c) The Neuro -endocrine System of Vertebrates

Optic Thala-

509

511

614

616

617

518

521

527

530

543

647

550

552

555

556

Part III. The Function of the Eyes of Animals

Chapter XVII

The Vision of Invertebrates

Methods of Investigation .....1. The Reactions of the Lower Invertebrates to Light

(a) Protozoa .....(b) Coelenterata.....(c) Echinodermata ....

567

670

570

571

571

XIV CONTENTS

2. The Vision of Worms ....(a) Unsegmented Worms(6) Segmented Worms

3. The Vision of Molluscs ....(a) Gastropods and Lamellibranchs

(6) Cephalopods

4. The Vision of Arthropods(a) Onychophora

(6) Myriapods

(c) Crustaceans

(d) Arachnids

5. The Vision of Insects(a) The Larvse of Insects ....(b) The Dorsal Ocelli of Adults .(c) The Compound Eyes of Insects

(i) Behavioural Experiments(ii) Electro-physiological Characteristics

(iii) Spectral Sensitivity

(iv) Discrimination of Luminosity-differences

(v) Perception of Colour .

(vi) Perception of Form .(vii) Perception of Distance

(viii) Spatial Appreciation and LocalizationAccommodation in Invertebrates

PAGE572

572

572

574

574

575

677

578

578

578

579

681

582

582

683

583

584

584

585

586

588

589

589

590

Chapter XVIII

The Vision of Vertebrates

The Role of Vision in Vertebrate Life(a) Cyclostomes

(b) Fishes

(c) Amphibians{d) Reptiles

(e) Birds

(/) Mammals

I. The Perception of Light1. The Nocturnal Eye

(a) The Optical SystemThe Tapetum Lucidum

(b) The Organization of the Retina2. The Diurnal Eye ....3. The Arhythmic Eye

(a) Contractile Pupils

(6) Occlusible Tapeta .(c) Photo -mechanical Changes in the Retina(rf) The Static Organization of the Retina

4. Absolute Sensitivity to Light .

6. Discriminati of Variations in Intensity .

597

598

698

599

599

600

600

602

605

605

606

609

611

612

612

612

614

616

616

617

CONTENTS XV

PAGEII. The Perception of Colour ......... 619

Objective Methods of Investigation ...... 621Subjective Methods of Investigation ...... 623

1. The Colour Vision of Cyclostomes ....... 6242. The Colour Vision of Fishes 6243. The Colour Vision of Amphibians ....... 6274. The Colour Vision of Reptiles ....... 6286, The Colour Vision of Birds 6296. The Colour Vision of Mammals ....... 632

III. The Perception of Form ......... 6371. Optical Factors 638

(a) The Refraction of Vertebrates ...... 638(6) Accommodation in Vertebrates ...... 640

(i) Static Devices ........ 640Stenopoeic Pupil, 641 ; Duplicated Optical System,

641 ; Interposition of Nictitating Membrane, 643 ;Duplicated Retina, 643 ; Ramp-retina, 643 ; Cor-

rugated Retina, 643 ; Length of Receptor Elements,643

(ii) DjTiamic Devices ....... 644(a) Movement of Lens as a ^^^^ole .... 644

Backward Movement, 644 ; Forward Movement,647

(^) Deformation of Lens ...... 649By Direct Ciliary Pressure, 649 ; by Capsular

Elasticity, 652

(iii) Accommodation in Amphibious Vertebrates . . . 654(c) Other Optical Factors determining Visual Acuity . . . 655

2. The Structure of the Retina 656(a) The Area Centralis ........ 657(b) The Fovea 658(c) The Degree of Summation ....... 659

3. The Visual Acuity of Vertebrates ....... 660(a) The Visual Acuity of Fishes 660(b) The Visual Acuity of Amphibians . . . . . .661(c) The Visual Acuity of Reptiles . ...... 661(d) The Visual Acuity of Birds 662(e) The Visual Acuity of Mammals ...... 663

rV. The Perception of Space1. The Visual Fields of Vertebrates

(a) The Uniocular Field

(6) The Binocular FieldCyclostomes, 678 ; Fishes, 678

682 ; Birds, 684 ; Mammals,2. The Ocular Movements .

(a) Involuntary Ocular Movements

(6) Voluntary Ocular MovementsFishes, 693 ; Amphibians, 694

Mammals, 696

Amphibians, 682

687

Reptiles,

666

669

669

672

689

690

692Reptiles, 694 ; Birds, 695

XVI CONTENTS

The Perception of Space

—

contd. page

3. Uniocular and Binocular Vision ....... 697Spatial Judgments . . . . . . . . .700

Fishes, 701 ; Amphibians and Reptiles, 702 ; Birds, 702 ;Manmials, 704

V. The Perception of Movement . . . . . . . .705

Part IV. Evolutionary By-ways

Chapter XIXMedian Eyes

1. Pineal and Parietal Organs . . . . . . . .. 711Cyclostomes, 713 ; Fishes, 713 ; Amphibians, 714 ; Reptiles, 715

(a) The Median Eye of the Lamprey . . . . . .716(6) The Median Eyes of Lizards and /S^/ienorfon . . . . .716

2. The Function of the Pineal and Parietal Organs . . . . .718

Chapter XXRudimentary Eyes

Habit and Regression . . . . . . . . . .7211. The Sedentary Habit 722

Molluscs, 722 ; Crustaceans, 722

2. The Abyssal Habit 722Molluscs, 723 ; Crustaceans, 723 ; Fishes, 723

3. The Cavernicolous or Limicoline Habit . . . . . .724Invertebrates, 724 ; Cave-fishes, 725 ; Amphibians, 726

4. The Fossorial or Burrowing Habit . . . . . . .728Invertebrates, 728 ; Amphibians, 730 ; Reptiles, 731 ; Mammals, 733

5. The Parasitic Habit 733Invertebrates, 733 ; Cyclostomes, 734 ; Fishes, 734

Chapter XXILuminous Organs

Bioluminescence .....1. The Occurrence of Bioluminescence .

The Biological Purpose of Bioluminescence2. The Biological Mechanism of Bioluminescence

Extracellular Bioluminescence

Intracellular Production of Bioluminescence

3. The Chemical Mechanism of Bioluminescence

736

737

741

744

745

746

747

Chapter XXII

Electric Organs

The Electric Organs of Fishes : Astroscopus

EPILOGUEAPPENDIX. Pala^ontological Table .Zoological Glossary ....Index ......

751

753

754

756

779

PART I

THE EFFECT OF LIGHT ON LIVING ORGANISMS

Introduction

The Effect of Light on Metabolism

The Effect of Light on Movement

The Effect of Light on Pigmentation

The Emergence of Vision

S.O.—VOL. I.

SO_DE_V1_P1_C1.pdfSO_DE_V1_P1_C2.pdfSO_DE_V1_P1_C3.pdfSO_DE_V1_P1_C4.pdfSO_DE_V1_P1_C5.pdf

PART II

THE EVOLUTION OF THE VISUAL APPARATUS

The Morphology of Invertebrate Eyes

The Systematic Anatomy of Invertebrate Eyes

The Eyes of Protochordates

The Evolution of the Vertebrate Eye

The Eyes of Cyclostomes

The Eyes of Fishes

The Eyes of Amphibians

The Eyes of Reptiles

The Eyes of Birds

The Eyes of Mammals

The Central Organization of Vision

SO_DE_V10_P2_C6.pdfSO_DE_V10_P2_C7.pdfSO_DE_V10_P2_C8.pdfSO_DE_V10_P2_C9.pdfSO_DE_V10_P2_C10.pdfSO_DE_V10_P2_C11.pdfSO_DE_V10_P2_C12.pdfSO_DE_V10_P2_C13.pdfSO_DE_V10_P2_C14.pdfSO_DE_V10_P2_C15.pdfSO_DE_V10_P2_C16.pdfSO_DE_V10_P2_C16.pdfSO_DE_V10_P2_C6.pdfSO_DE_V10_P2_C7.pdfSO_DE_V10_P2_C8.pdfSO_DE_V10_P2_C9.pdfSO_DE_V10_P2_C16.pdfSO_DE_V1_P2_C6.pdfSO_DE_V1_P2_C7.pdfSO_DE_V1_P2_C8.pdfSO_DE_V1_P2_C9.pdfSO_DE_V1_P2_C10.pdfSO_DE_V10_P2_C11.pdfSO_DE_V10_P2_C16.pdfSO_DE_V10_P2_C15.pdfSO_DE_V10_P2_C16.pdfSO_DE_V10_P2_C15.pdfSO_DE_V10_P2_C14.pdfSO_DE_V10_P2_C13.pdfSO_DE_V1_P2_C16.pdfSO_DE_V1_P2_C15.pdfSO_DE_V1_P2_C14.pdfSO_DE_V1_P2_C13.pdfSO_DE_V1_P2_C12.pdfSO_DE_V1_P2_C11.pdf

PART III

THE FUNCTION OF THE EYES OF ANIMALS

The Vision of Invertebrates

The Vision of Vertebrates

SO_DE_V1_P3_C17.pdfSO_DE_V1_P3_C18.pdf

PART IV

EVOLUTIONARY BY-WAYS

Median Eyes

Rudimentary Eyes

Luminous Organs

Electric Organs

SO_DE_V1_P4_C19.pdfSO_DE_V1_P4_C20.pdfSO_DE_V1_P4_C21.pdfSO_DE_V1_P4_C22.pdf

PortadaEsquema "System Ophthalmology"PrefacioReconocimientosContenidoParte I. Efectos de la Luz en los Organismos vivos1.- Introducción2.- Efectos de la luz en el metabolismo: FOTOPERIODISMO3.- Efectos de la luz en el Movimiento4.- Efectos de la luz en la Pigmentación5.- Aparición de la Visión

Parte II. La evolución del Aparato Visual 6.- La morfología del ojo de los Invertebrados 7.- Anatomía Sistemática del Ojo de los Invertebrados8.- El Ojo de los Protocordados 9.- Evolución del Ojo de los Vertebrados10.- El Ojo de los Ciclóstomos11.- El ojo de los Peces12.- El Ojo de los Anfibios13.- El Ojo de los Reptiles14.- El Ojo de los Pájaros15.- El Ojo de los Mamíferos16.- Organización Central de la Visión

Parte III. La función de los Ojos en los Animales17.- La Visión de los Invertebrados18.- La Visión de los Vertebrados

Parte IV. Otros Caminos Evolutivos19.- Ojo Medial20.- Ojos Rudimentarios21.- Órganos Luminosos22.- Órganos Eléctricos

EpílogoApéndiceGlosario de ZoologíaÍndice