Experimental morphology

Front matter

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Preface To Part II

Development consists of growth and differentiation, accompanied in the larger organisms by nuclear- and cell-division. The present Part deals with growth.

The importance of the study of growth cannot be overestimated, and it is a cause for wonder that the treatment of the subject has been so much neglected by text-books. Indeed, it is a surprising fact that it has not been thoroughly and systematically investigated. For, in last analysis, the maintenance of the human race depends upon that property which protoplasm among all substances alone displays of increasing itself for an indefinite time and to an indefinite amount. And the possibility of increasing the human race beyond limits that are not far off depends upon a better knowledge of the conditions of growth. The reader has only to consider that the world’s supply of 2500 million bushels of wheat, 2000 million bushels of maize, 90 million tons of potatoes, and its untold millions of tons of beef, pork, and fish are reproduced each year by growth. The mineral matters of the soil are being washed out into the sea and are largely lost, but the capacity of growth under appropriate conditions is never lost ; it redoubles as the amount of the growing substance is increased. The only thing, then, which limits growth is the limitations in the conditions of growth. What are these conditions ? This is the important question to which attention has been directed in this Part.

Aside from this practical interest, the study of growth is important as bearing on the question of the dependence of vital activities, and especially development, upon external conditions, xb and the possibility of the control of development by appropriately altering those conditions. Growth phenomena show themselves, indeed, particularly susceptible to this control, and are consequently especially valuable for experimental study.

In the preparation of the Second Part, I have been put again under heavy obligations to my friend and colleague, Dr. G. H. Parker, who has read most of the manuscript and made important suggestions. I am also indebted to Dr. H. E. Sawyer for reading Chapter XI in the manuscript, and to my wife for much painstaking work on the manuscript and proofs and for compiling the index.

C. B. D.

Cambridge, Mass., Dec. 11, 1898.

I

PAGE

Preface vii

CHAPTER I Action of Chemical Agents upon Protoplasm

1. Oxygen 2

3. Oxides of Carbon 6

5. Catalytic Poisons 7

6. Poisons which form Salts . . . . . . .12

a. Acids 12

b. Soluble Mineral Bases 13

c. Salts of Heavy Metals 13

7. Substitution Poisons 15

8. Sodic Fluoride 21

9. Special Poisons .22

CHAPTER II Effect of Varying Moisture upon Protoplasm

§ 1. On the Amount of Water in Organisms 58

§ 2. On the Effect of Desiccation upon the Functions of Protoplasm . 59

1. Effect of Dryness on Metabolism ...... 59

2. Effect of Dryness upon the Motion of Protoplasm . . 60

3. Desiccation-rigor and Death 60

§ 3. On the Acclimatization of Organisms to Desiccation ... 65

§ 4. The Determination of the Direction of Movement by Moisture —

Hydrotaxis 66 xi

Xll

CHAPTER III Action of the Density of the Medium upon Protoplasm

PAGE

§ 1. Introductory Remarks upon the Structure of Protoplasm and the

Physical Action of Solutions 70

§ 2. Effect of Varying Density upon the Structure and General

Functions of Protoplasm 74

§ 3. Acclimatization to Solutions of Greater or Less Density than the

Normal 85

§ 4. Control of the Direction of Locomotion by Density — Tonotaxis . 89

CHAPTER IV Action of Molar Agents upon Protoplasm

§ 1. Effect of Molar Agents upon Lifeless Matter .... 97

§ 2. Effect of Molar Agents upon the Metabolism and Movement of

Protoplasm 98

§ 3. Effect of Molar Agents in Determining the Direction of Locomotion— Thigmotaxis (Stereotaxis) and Rheotaxis . . . 105

CHAPTER V Effect of Gravity upon Protoplasm

§ 1. Methods of Study 112

§ 2. Effect of Gravity upon the Structure of Protoplasm . . .113

§ 3. Control of the Direction of Locomotion by Gravity — Geotaxis . 114

CHAPTER VI Effect of Electricity upon Protoplasm

§ 1. Concerning Methods 126

§ 2. The Effect of Electricity upon the Structure and General Functions of Protoplasm ........ 129 xm

CHAPTER VII Action of Light upon Protoplasm

§ 1. The Application and Measurement of Light § 2. The Chemical Action of Light upon Non-living Substances

1. The Synthetic Effects of Light

2. Analytic Effect of Light

3. Substitution Effects of Light .

PAGE

4. The Isomerismic and Polymerismic Changes produced by Light 164

§ 3. The Effect of Light upon the General Functions of Organisms .

1. Effect of Light upon Metabolism

a. The Thermic Effect of Light on Metabolism

b. The Chemical Effect of Light on Metabolism

2. Vital Limits of Light Action on Protoplasm

3. Effect of Light upon the Movement of Protoplasm

a. Effect of Low Intensity of Light on Movement — Dark-rigor b. Effect of High Intensity of Light on Movement —

Light-rigor

§4. Control of the Direction of Locomotion by Light — Phototaxis and Photopathy

1. False and True Phototaxis .......

2. Distribution of Phototaxis and Photopathy ....

b. Cells and Cell-organs .......

a. Chlorophyll Bodies

(3. The Rearrangement of Pigment in Animal Cells

in Response to Light

y. The Migration of Pigment Cells in the Metazoan Body

c. Metazoa

3. The General Laws of Phototaxis and Photopathy

a. The Sense of the Response ......

b. The Effective Rays

c. Phototaxis vs. Photopathy ......

d. The Mechanics of Response to Light ....

Literature ....

'166

171 175 lbO

XIV

CHAPTER vm

Action of Heat upon Protoplasm

§ 2 ?h?Effei^faHanid ‘he -If"6™' Meth°ds of its Application . § - he Effec of Hea upon the General Functions of Organisms

1* Effect ot Heat upon Metabolism

2' E iri°bii5at upon the Movement of Protopiasm and itS

1. Temporary Rigor and Death at the Higher’ Limit of Tern-

perature, Maximum and Ultramaximum

- Temporary Rigor and Death at the Lower Limit of Tempera- . . A ture> Minimum and Ultraminimum . . P

§ • Acclimatization of Organisms to Extreme Temperatures

1- Acclimatization to Heat ... '

2. Acclimatization to Cold

§ 5. Determination of the Direction of Locomotion by Heat -The* motaxis • ,

Notes to Table XXI .

PAGE

258 263 267

Chapter IX

General Considerations on the Effects of Chemical and Physical Agents upon Protoplasm

§U

§2.

§3.

§4.

Conclusions on the Structure and Composition of Protoplasm the Limiting Conditions of Metabolism

The Dependence of Protoplasmic Movement upon Metabolis and upon External Stimuli

The Determination of the Direction of Locomotion

CHAPTER XI Effect of Chemical Agents upon Growth

§ 1. Effect of Chemical Agents upon the Rate of Growth

1* The Materials of which Organisms are composed .

a, . Analysis of the Entire Organism ....

b. Detailed Account of the Various Elements used as Food

Oxygen, 304; Hydrogen, 306; Carbon, 306; Nitrogen, 307 ; Phosphorus, 313 ; Arsenic, Antimony, and Bismuth, 314; Sulphur, 314; Chlorine, 316; Bromine, 316; Iodine, 317; Fluorine, 317; Lithium, 31S ; Sodium, 318; Potassium, 318; Rubidium and Caesium, 320; Strontium, 321 ; Manganese, 321 ;

Iron, 321 ; Magnesium, 323 ; Silicon, 324 ; Copper5 324. 1 ’

2. The Organic Food used by Organisms in Growth .

a- Fungi

b. Green Plants

c. Animals

Amoeba, 328; Amphibia, 329; Mammals, 330.

3. Growth as a Response to Stimuli a. Acceleration of Growth by Chemical Stimulants .

b. The Election of Organic Food

§ 2. Effect of Chemical Agents upon the Direction of Growth — Chemotropism

1. Chemotropisrn in the Tentacles of Insectivorous Plants

2. Chemotropisrn of Roots ....

3. Chemotropisrn of Pollen-tubes

4. Chemotropisrn of Hyphse

. 5. Chemotropisrn of Conjugation Tubes in Spirogvra

Literature . .

PAGE

294 296 304

337 340 xv xvi

CHAPTER XI i

The Effect of Water upon Growth

! o' P(veC‘ °! 1\Vate‘' Upon the Rate and Quantity of Growth .

S - Effec^of W ater on the Direction of Growth — Hydrotropism

“* Rhizoids of Higher Cryptogams

3. Stems

4. Pollen-tubes

• •

5. Hyphje of Fungi Literature

CHAPTER XIII Effect of the Density of the Medium upon Growth

§ 1. Effect of Density upon the Rate of Growth

Phigmotropisi

CHAPTER XIV Effect of Molar Agents upon Growth

§ 1. Effect of Molar Agents upon the Rate of Growth .

1. Contact .

2. Rough Movements .

3. Deformation

4. Local Removal of Tissue

§ 2. Effect of Contact upon the Direction of Growth —

L Twining Stems

2. Tendrils .

3. Roots

4. Cryptogams

5. Animals .

**••••

6. Tiie Accumulation of Contact-stimulus and Acclimatizatic

toit •

7. Explanation of Thigmotropism

§3. Effect of Wounding upon the Direction of Growth -1 Traumi tropism

L False Traumatropism ....

2. True Traumatropism ....

§ 4. Effect of Flowing Water upon the Direction of Growth — Rhec tropism

Summary of the Chapter ....

PAG*

384 384 384

XVII

CHAPTER XV Effect of Gravity upon Growth

§ 1. Effect of Gravity upon the Rate of Growth .

§ 2. The Effect of Gravity upon the Direction of Growth —

1. False Geotropism ....

2. True Geotropism .....

a. Roots ....

b. Stems ....

c. Rhizoma

d. Cryptogams

e. Animals .

Summary f. After-effect in Geotropism

PAGB

CHAPTER XVI Effect of Electricity upon Growth

§ 1. Effect of Electricity upon the Rate of Growth

§ 2. Effect of Electricity upon the Direction of Growth — tropism

1. False and True Electrotropism

2. Electrotropism in Phanerogams

3. Electrotropism in Other Organisms

4. Magnetropism . . .

5. Explanation of Electrotropism and Summary Literature

CPIAPTER XVII

Effect of Light upon Growth

§ 1. Effect of Light on the Rate of Growth .

1. Retarding Effect of Light ....

2. Accelerating Effect of Light .

3. The Effective Rays

a. The Effective Rays in the Retardation of Growth by Light

b. The Effective Rays in the Acceleration of Growth by Light

« o Jt The CaUSe °f the Effect °f Light on the Rate of Growth $ 2. Effect of Eight upon the Direction of Growth — Phototropism

1. Plants

2. Animals

a. Serpulidae

b. Hydroids ....

437 437 442 xviii a. Persistence of Stimulation

b. Acclimatization to Light

c. Mechanics of Phototropism

CHAPTER XVIII Effect of Heat on Growth

§ 1. Effect of Heat on the Rate of Growth

1. Plants

2. Animals

3. Some General Phenomena accompanying Heat Effects .

a. Latent Period

b. Sudden Change of Temperature ....

c. Cause of Acceleration of Growth by Heat

§ 2. Effect of Heat on the Direction of Growth — Thermotropism

1. Effect of Radiant Heat

2. Conducted Heat

3. Causes of Thermotropism

CHAPTER XIX Effect of Complex Agents upon Growth, and General

Conclusions

§ 1. The Cooperation of Geotropism and Phototropism

§ 3. General Considerations relating to the Action upon Growth of External Agents

1. Modification of Rate of Growth ......

2. Modification of Direction of Growth — Tropism .

3. Adaptation in Tropisms

4. Critical Points in Tropism

List of Tables in Parts I and II

PAGE

461 463

467 467

Index to Parts I and II

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