Book - Chemical embryology 1 (1900)

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I have decided to take early retirement in September 2020. During the many years online I have received wonderful feedback from many readers, researchers and students interested in human embryology. I especially thank my research collaborators and contributors to the site. The good news is Embryology will remain online and I will continue my association with UNSW Australia. I look forward to updating and including the many exciting new discoveries in Embryology!

Needham J. Chemical Embryology Vol. 1. (1900)

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This historic 1900 volume 1 of a textbook by Needham describes chemical embryology.

Internet Archive

Also by this author: Needham J. Chemical Embryology Vol. 2. (1900)

Modern Notes:
Historic Textbooks

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Pages where the terms "Historic" (textbooks, papers, people, recommendations) appear on this site, and sections within pages where this disclaimer appears, indicate that the content and scientific understanding are specific to the time of publication. This means that while some scientific descriptions are still accurate, the terminology and interpretation of the developmental mechanisms reflect the understanding at the time of original publication and those of the preceding periods, these terms, interpretations and recommendations may not reflect our current scientific understanding.     (More? Embryology History | Historic Embryology Papers)

Chemical Embryology - Volume One


Joseph Needham

M.A., Ph.D.

Fellow of Gonville & Cains College, Cambridge, and University Demonstrator in Biochemistry.

New York: The Macmillan Company Cambridge, England: At The University Press 1931 Printed In Great Britain




PART I The Theory of Chemical Embryology Philosophy, Embryology, and Chemistry

The Historical Perspective

Obstacles to Chemical Embryology

The Stumbling-block of Hormism

Finalism as a Rock of Offence

Organicism as an Occasion of Falling

Organicism and Emergence

Neo-Mechanism as a Theory for Chemical Embryology

PART II The Origins of Chemical Embryology

Preliminary Note

Section 1. Embryology in Antiquity

1-1. Non-Hellenic Antiquity

1-2. Hellenic Antiquity; the Pre-Socratics

1-3. Hippocrates; the Beginning of Observation

1-4. Aristotle

1-5. The Hellenistic Age

1-6. Galen

Section 2. Embryology from Galen to the Renaissance

2-1. Patristic, Talmudic, and Arabian Writers

2-2. St Hildegard; the Lowest Depth

2-3. Albertus Magnus

2-4. The Scholastic Period

2-5. Leonardo da Vinci

2-6. The Sixteenth Century; the Macro-iconographers

Section 3. Embryology in the Seventeenth and Eighteenth Centuries

3-1. The Opening Years of the Seventeenth Century

32. Kenelm Digby and Nathaniel Highmore

3-3. Thomas Browne and the Beginning of Chemical Embryology

3-4. William Harvey

35, Gassendi and Descartes; Atomistic Embryology

36. Walter Needham and Robert Boyle

3-7. Marcello Malpighi; Micro-iconography and Preformationism

3-8. Robert Boyle and John Mayow

3-9. The Theories of Foetal Nutrition

3-10. Boerhaave, Hamberger, Mazin

3-11. Albrecht v. Haller and his Contemporaries

3-12. Ovism and Animalculism

3- 1 3. Preformation and Epigenesis

3-14. The Close of the Eighteenth Century

3-15. The Beginning of the Nineteenth Century

PART III General Chemical Embryology

Preliminary Note

Section 1. The UnfertiUsed Egg as a Physico-chemical System

1. Introduction

2. General Characteristics of the Avian Egg

3. The Proportion of Parts in the Avian Egg

4. Chemical Constitution of the Avian Egg as a Whole

5. The Shell of the Avian Egg

6. The Avian Egg-white

7. The Avian Yolk

8. The Avian Yolk-proteins

9. The Fat and Carbohydrate of the Avian Yolk

10. The Ash of the Avian Egg

11. General Characteristics of non-Avian Eggs

12. Egg-shells and Egg-membranes

13. Proteins and other Nitrogenous Compounds

14. Fats, Lipoids, and Sterols

15. Carbohydrates

16. Ash

Section 2. On Increase in Size and Weight

2-1. Introduction

2-2. The Existing Data

2-3. The General Nature of Embryonic Growth

2-4. The Empirical Formulae

2-5. Percentage Growth-rate and the Mitotic Index

2-6. Yolk-absorption Rate

2-7. The Autocatakinetic Formulae

2-8. Instantaneous Percentage Growth-rate

2-9. Growth Constants

2-10. The Growth of Parts

2-1 1. Variability and Correlation

2-12. Explantation and the Growth-promoting Factor

2-13. Incubation Time and Gestation Time

2-14. The Effect of Heat on Embryonic Growth

2-15. Temperature Coefficients

2-16. Temperature Characteristics

2-17. The Effect of Light on Embryonic Growth

2-i8. The Effect of X-rays and Electricity on Embryonic Growth

2-19. The Effect of Hormones on Embryonic Growth

Section 3.

3-1 On Increase in Complexity and Organisation

3-2 The Independence of Growth and Differentiation

3-3 Differentiation-rate

3-4 Chemical Processes and Organic Form

3-5 The Types of Morphogenetic Action

3-6 Pluripotence and Totipotence

3-7 Self-differentiation and Organiser Phenomena Functional Differentiation

3-8 Axial Gradients

3-9 Organised and Unorganised Growth

3-10. Chemical Embryology and Genetics


Section 4. The Respiration and Heat-production of the Embryo

4-1. Early Work on Embryonic Respiration

4-2. Respiration of Echinoderm Embryos in General

4-3. Rhythms in Respiratory Exchange

4-4. Heat Production and Calorific Quotients of Echinoderm Embryos

4-5. Respiration of Annelid, Nematode, Rotifer, and Mollusc Embryos

4-6. Respiration of Fish Embryos

4-7. Respiration of Amphibian Embryos

4-8. Heat-production of Amphibian Embryos

4-9. Respiration of Insect Embryos

4-10. Respiration of Reptile Embryos

4-11. Respiration of Avian Embryos in General

4-12. Heat-production of Avian Embryos

4-13. Later Work on the Chick's Respiratory Exchange

4-14. The Air-space and the Shell

4-15. Respiration of Mammalian Embryos

4-16. Heat-production of Mammalian Embryos

4-17. Anaerobiosis in Embryonic Life

4-18. Metabolic Rate in Embryonic Life

4-19. Respiratory Intensity of Embryonic Cells in vitro

4-20. Embryonic Tissue-respiration and Glycolysis

4-21. The Genesis of Heat Regulation

4-22. Light-production in Embryonic Life

Section 5. Biophysical Phenomena in Ontogenesis

5-1. The Osmotic Pressure of Amphibian Eggs

5-2. The Genesis of Volume Regulation

53. The Osmotic Pressure of Aquatic Arthropod Eggs

54. The Osmotic Pressure of Fish Eggs

5-5. Osmotic Pressure and Electrical Conductivity in Worm and Echinoderm Eggs

5-6. The Osmotic Pressure of Terrestrial Eggs

5-7. Specific Gravity

5-8. Potential Differences, Electrical Resistance, Blaze Currents and Cataphoresis

5-9. Refractive Index, Surface Tension and Viscosity

Section 6. General Metabolism of the Embryo

6-1. The j&H of Aquatic Eggs

6-2. The j&H of Terrestrial Eggs

6-3. rH in Embryonic Life

6-4. Water-metabolism of the Avian Egg

Section 6-5. Water-content and Growth-rate page

6-6. Water-absorption and the Evolution of the Terrestrial Egg

6-7. Water-metabolism in Aquatic Eggs

6-8. The Chemical Constitution of the Embryonic Body in Birds and Mammals

6-9. Absorption-mechanisms and Absorption-intensity

6- 10. Storage and Combustion; the Plastic Efficiency Coefficient

6-11. Metabolism of the Avian Spare Yolk

6-12. Maternal Diet and Embryonic Constitution

Section 7. The Energetics and Energy-sources of Embryonic Development

7-1. The Energy Lost from the Egg during Development

7-2. Energy of Growth and Energy of Differentiation

7-3. The Relation between Energy Lost and Energy Stored

7-4. Real Energetic Efficiency

7-5. Apparent Energetic Efficiency

7-6. Synthetic Energetic Efficiency

7-7. The Sources of the Energy Lost from the Egg

Sections. Carbohydrate Metabolism

8-1. General Observations on the Avian Egg

8-2. Total Carbohydrate, Free Glucose, and Glycogen

8-3. Ovomucoid and Combined Glucose

8-4. Carbohydrate and Fat

8-5. The Metabolism of Glycogen and the Transitory Liver

8-6. Free Glucose, Glycogen, and Insulin in the Embryonic Body

8-7. General Scheme of Carbohydrate Metabolism in the Avian Egg

8-8. Embryonic Tissue Glycogen

8-9. Embryonic Blood Sugar

8-10. Carbohydrate Metabolism in Amphibian Development

8-11. Carbohydrate Metabolism of Invertebrate Eggs

8-12. Pentoses

8-13. Lactic Acid

8-14. Fructose

Section 9. Protein Metabolism

9-1. The Structure of the Avian Egg-proteins before and after Development

9-2. Metabolism of the Individual Amino-Acids

9-3. The Relations between Protein and non-Protein Nitrogen

9-4. The Accumulation of Nitrogenous Waste Products

9-5. Protein Catabolism

9-6. Nitrogen-excretion; Mesonephros, Allantois, and Amnios

9-7. The Origin of Protective Syntheses

9*8. Protein Metabolism of Reptilian Eggs

9-9. Protein Metabolism of Amphibian Eggs

9' 10. Protein Metabolism in Teleostean Ontogeny

9-11. Protein Metabolism in Selachian Ontogeny

9-12. Protein Metabolism of Insect, Worm, and Echinoderm Eggs

9-13. Protein Utilisation in Mammalian Embryonic Life

9-14. Protein Utilisation of Explanted Embryonic Cells

9-15. Uricotelic Metabolism and the Evolution of the Terrestrial Egg

Section 10. The Metabolism of Nucleins and Nitrogenous Extractives

10-1. Nuclein Metabolism of the Chick Embryo

10-2. The Nucleoplasmatic Ratio

10-3. Nuclein Synthesis in Developing Eggs

10-4. Creatinine, Creatine, and Guanidine

Section 11. Fat Metabolism

11-1. Fat Metabolism of Avian Eggs

11-2. Fat Metabolism of Reptilian Eggs

11-3. Fat Metabolism of Amphibian Eggs

11-4. Fat Metabolism of Selachian Eggs

11-5. Fat Metabolism of Teleostean Eggs

11-6. Fat Metabolism of Mollusc, Worm, and Echinoderm Eggs

11-7. Fat Metabolism of Insect Eggs

11-8. Combustion and Synthesis of Fatty Acids in Relation to Metabolic Water

11-9. Fat Metabolism of Mammalian Embryos

Section 12. The Metabolism ofLipoids, Sterols, Cycloses, Phosphorus and Sulphur

12-1. Phosphorus Metabolism of the Avian Egg

12-2. Tissue Phosphorus Coefficients

I2-3. Choline in Avian Development

12-4, The Metabolism of Sterols during Avian Development

12-5. The Relation between Lipoids and Sterols; the Lipocytic Coefficient

12-6. Cycloses and Alcohols in Avian Development

12-7. Sulphur Metabolism of the Avian Egg

12-8. Phosphorus, Sulphur, Choline, and Cholesterol in Reptile Eggs

Section 12-9. Lipoids and Sterols in Amphibian Eggs

12-10. Lipoids, Sterols, and Cycloses in Fish Eggs

i2-11. Phosphorus, Lipoids and Sterols in Arthropod Eggs

12-12. Phosphorus, Lipoids, and Sterols in Worm and Echinoderm Eggs

12-13. Lipoids and Sterols in Mammalian Development

Section 13. Inorganic Metabolism

13-1. Changes in the Distribution of Ash during Avian Development

13-2. Calcium Metabolism of the Avian Egg

13-3. Inorganic Metabolism of other Eggs

13-4. The Absorption of Ash from Sea-water by Marine Eggs

13-5. The Ani on/Cation Ratio

13-6. Inorganic Metabolism of Mammalian Embryos

13-7. Calcium Metabolism of Mammalian Embryos

Section 14. Enzymes in Ontogenesis

14-1. Introduction

4-2. Enzymes in Arthropod Eggs

4-3. Enzymes in Mollusc, Worm, and Echinoderm Eggs

4-4. Enzymes in Fish Eggs

4-5. Enzymes in Amphibian Eggs

4-6. Enzymes in Sauropsid Eggs

4-7. Changes in Enzymic Activity during Development

4-8. Enzymes of the Embryonic Body

4-9. Enzymes in Mammalian Embryos

4-10. The Genesis of Nucleases

4-11. Foetal Autolysis

Section 15. Hormones in Ontogenesis

15-1. Introduction

15-2. Adrenalin

15-3. Insulin

15-4. The Parathyroid Hormone

15-5. The Hormones of the Pituitary

15-6. Secretin

15-7. Thyroxin

15-8. Oestrin and other Sex Hormones

Section i6. Vitamins in Ontogenesis

16-1. Vitamin A

16-2. Vitamin B

16-3. Vitamin C

16-4. Vitamin D

16-5. Vitamins in Mammalian Development

16-6. Vitamin E

Section 17. Pigments in Ontogenesis

17-1. The Formation of Blood Pigments

17-2. The Formation of Bile Pigments

17-3. The Formation of Tissue Pigments

17-4. The Pigments of the Avian Egg-shell

17-5. The Pigments of the Avian Yolk

17-6. Egg-pigments of Aquatic Animals

17-7. Melanins in Ontogenesis

Section 18. Resistance and Susceptibility in Embryonic Life

18-1. Introduction

18-2. Standard Mortality Curves

18-3. Resistance to Mechanical Injury

18-4. Resistance to Thermal Injury

18-5. Resistance to Electrical Injury

18-6. Resistance to Injury caused by Abnormal j&H

18-7. Resistance to Injury caused by Abnormal Gas Concentrations (non-Avian Embryos)

18-8. Critical Points in Development

18-9. Resistance to Injury caused by Abnormal Gas Concentrations (Avian Embryos)

18-10. Resistance to Injury caused by Toxic Substances

18-11. Resistance to Injury caused by X-rays, Radium Emanation, and Ultra-violet Light

Section 19. Serology and Immunology in Embryonic Life

19-1. Antigenic Properties of Eggs and Embryos

19-2. The Formation of Natural Antibodies

19-3. The Natural Immunity of Egg-white

19-4. Inheritance of Immunity in Oviparous Animals

19-5. Serology and Pregnancy

19-6. Resistance of the Avian Embryo to Foreign Neoplasms

Section 20. Biochemistry of the Placenta

20-1. Introduction

20-2. General Metabolism of the Placenta

20-3. Placental Respiration

20-4. Nitrogen Metabolism of the Placenta

20-5. Carbohydrate Metabolism of the Placenta

20-6. Fat and Lipoid Metabolism of the Placenta

20-7. Placental Enzymes

Section 21. Biochemistry of the Placental Barrier

21-1. The Autonomy of the Foetal Blood

21-2. Evolution of the Placenta

21-3. Histotrophe and Haemotrophe

21-4. Mesonephros and Placenta

21-5. Colostrum and Placenta

21-6. Placental Transmission and Molecular Size

21-7. QuaHtative Experiments on Placental Permeability

21-8. The Passage of Hormones

21-9. Factors Governing Placental Transmission

2I-IO. Quantitative Experiments on the Passage of Nitrogenous Substances

21-11. Quantitative Experiments on the Passage of Phosphorus, Fats, and Sterols

21-12. Quantitative Experiments on the Passage of Carbohydrates

21-13. Quantitative Experiments on the Passage of Ash

21-14. The Passage of Enzymes

21-15. The Unequal Balance of Blood Constituents

Section 22. Biochemistry of the Amniotic and Allantoic Liquids

22-1. Introduction

22-2. Evolution of the Liquids

22-3. Avian Amniotic and Allantoic Liquids

22-4. Amount and Composition of Mammalian Amniotic and Allantoic Liquids

22-5. Maternal Transudation and Foetal Secretion

22-6. Interchange between Amniotic and Allantoic Liquids

22-7. Vernix Caseosa

Section 23. Blood and Tissue Chemistry of the Embryo

23-1. Blood

23-2. Lung

23-3. Muscle

23-4. Heart

23-5 Nervous Tissue

23-6. Connective Tissue

23-7. Lymph

23-8. Sense Organs

23-9 Intestinal Tract

Section 24. Hatching and Birth

24-1. Introduction

24-2. Hatching Enzymes

24-3. Osmotic Hatching

24-4. Egg-breakers

24-5. Hatching of the Avian Egg

24-6. Mammalian Birth


The Two Problems of Embryology

The Cleidoic Egg and its Evolution

Chemical Synthesis as an Aspect of Ontogeny

Biochemistry and Morphogenesis

Transitory Functions in Embryonic Life

The Theory of Recapitulation

Recapitulation and Substitution

Chemical Recapitulation

Provisional Generalisations for Chemical Embryology

The Organisation of Development and the Development of Organisation

The Future of Embryology

PART IV Appendices

i. Normal Tables of Magnitudes in Embryonic Growth

ii. A Chemical Account of the Maturation of the Egg-cell

iii. The Chemical Changes during the Metamorphosis of Insects (by Dorothy Needham)

iv. The Development of the Plant Embryo from a Physico-chemical Viewpoint (by Muriel Robinson)

PART V Bibliography and Author-Index


Index Animalium

Acknowledgements of Indebtedness

Those who have assisted me in the preparation of this work are so numerous that it is impossible to mention them all by name. Its original impetus was derived from a discussion with Professor Sir F. G. Hopkins in 1923 on the observation of Klein that inositol, though absent from the undeveloped hen's egg, was present in considerable quantity at hatching; and throughout the period of preparation his encouragement, help, and advice were never-failing. I have derived great benefit from the discussion of various points with Miss Marjory Stephenson, M. Louis Rapkine, Dr R. A. Fisher, and my wife. Professor J. T. Wilson has been repeatedly helpful to me on anatomical points, and in the Zoological Laboratory I was always sure of obtaining expert advice from Mr James Gray, Mr J. T. Saunders, Mr C. F. A. Pantin and Dr Eastham. I have relied much upon the kindness and wide biological knowledge of Dr D. Keilin and Dr F. H. A. Marshall. As regards the historical chapters, I am most grateful to Dr Charles Singer, who annotated them with valuable comments, and to Professor R. C. Punnett who placed unreservedly at my disposal his knowledge of the history of generation, and his library of old and rare biological books. To Dr Arthur Peck I am indebted for the correction of my Greek, and it was Professor A. B. Cook who guided me to the embryology of the ancients. Without the assiduous backing of Mr Powell, the Librarian of the Royal Society of Medicine, and his assistants, I should have dealt much more inadequately than I have with the papers which cannot be consulted in Cambridge. I have also to thank the administrators of the Thruston Fund of Gonville and Caius College for a grant which was devoted to incidental expenses. For the indexes I wish to thank Miss Helen Moyle, and for other services which have made the book possible, Mrs V. Townsend. My thanks are also due to the Editors of the following journals: Biochemical Journal, Journal of Experimental Biology, Biological Reviews, Science Progress, and the Monist, for permission to reprint passages from papers. I must record my gratitude to the following friends, who very kindly read through and criticised the proofs of the various sections:

Part I

Professor A. E. Boycott Dr J. H. Woodger

Part II

Professor R. C. Punnett Dr Charles Singer Dr Reuben Levy Dr Arthur Peck Sir William Dampier Professor A. B. Cook The Rev. W. Elmslie Professor F. M. Cornford

Part III


1 Professor R. H. A. Plimmer Mr J. B. S. Haldane

2 Dr Samuel Brody Mr James Gray Dr E. N. Willmer

3 Mr G. R. de Beer

Mr C. H. Waddington Mr J. B. S. Haldane

4 Dr D. Keilin Professor Munro Fox

5 Mr T. R. Parsons Dr Malcolm Dixon

6 M. Louis Rapkine Mr C. Forster Cooper

7 Miss Marjory Stephenson M. Louis Rapkine

Dr D. Keilin

8 Dr Eric Holmes

Dr Bruce Anderson & Mrs Margaret Whetham Anderson

9 Dr Dorothy Jordan Lloyd

Professor J. Murray Luck

Mr C. Forster Cooper

10 Mile Eliane LeBreton

11 Professor J. B. Leathes

12 Dr Irvine Page

13 Dr Elsie Watchorn

14 Dr Barnet Woolf

Mr J. B. S. Haldane

15 Dr Howard Florey

16 Dr Leslie J. Harris

Dr A. L. Bacharach

18 Dr Howard Whittle

19 Mr C. F. A. Pantin

Professor A. R. Moore & Mrs Moore

20 Dr John Hammond

21 Dr St G. Huggett

22 Dr Arthur Walton

23 Dr Barbara Holmes

24 Dr F. H. A. Marshall


Professor L. G. M. B. Becking

Dr D. Keilin

Dr G. S. Carter

Professor Lancelot Hogben

Mr G. R. de Beer

Professor A. R. Moore & Mrs Moore

Appendix III Dr L. E. S. Eastham

I am indebted to the Master of Gonville and Caius College for permission to reproduce the portrait of William Harvey (attributed to Rembrandt) in the Senior Combination Room. Finally, I am glad to record here my gratitude to the StafTof the Cambridge University Press for the unremitting care which they gave to my book during the course of its preparation.

J. N.

Note: The use of the shortened and (&) indicates collaboration between two or more authors.


The Sciences, unlike the Graces or the Eumenides, are not limited in number. Once born, they are immortal, but, as knowledge increases, they are ever multiplying, and so great is now the dominion of the scientific mind that every few years sees a new one brought into the world. Some spring, fully armed, from the brains of one or two men of genius, but most of them, perhaps, come only gradually to their full development through the labours of very many obscure and accurate observers.

If the analogy may be permitted, physico-chemical embryology has so far been living an intra-uterine existence. Its facts have been buried in a wide range of scientific journals, and its theories have lain dormant or in potentia in reviews of modest scope. Physicochemical embryology has, indeed, arrived at the stage immediately priox to birth, and all it needs is a skilful obstetrician, for, when once it has reached the light of day and has passed for ever out of the foetal stage, it will be well able to take care of itself. This obstetrical task is that which I have chosen and obviously enough it divides into three principal heads: first, to collect together out of all the original papers on the subject the facts which are known about the physico-chemical basis of embryonic development; second, to relate these facts to each other and to the facts derived from the labours of investigators in morphological embryology and " Entwicklungsmechanik," and, third, to ascertain whether, from what is at present known, any generally valid principles emerge.

I may as well say at the outset that in order to do this certain arbitrary boundary-lines are inevitable. The following arrangement has been adopted. Chronologically speaking, the prelude to all embryonic development is the maturation of the egg-cell, but this is not strictly embryology, and so has been relegated to an appendix. The egg-cell as a physico-chemical system is dealt with at the opening of Part III, and thereafter the physico-chemical aspects of development follow in order. No mention will be made of fertilisation, for this has been treated exhaustively by other writers (Lillie, Dalcq) and, after all, embryology presupposes fertiUsation whether natural or artificial. Nor in later chapters will any complete treatment be given of the events going on in the maternal organism during pregnancy : for the present purpose the discussion will go as far into the mother as the placenta but no farther. Again, hatching or birth will put an end to the discourse as to the foetal state itself, save that, in the cases of animals which hatch before the yolk-sac is absorbed, their embryonic life is assumed to end when they first take food for themselves. Appendices are added dealing with the plant embryo and the insect pupa, which, in the later stages of metamorphosis, have points both of resemblance to and of difference from the growth of the embryo. It is natural to hope that the outcome of all this labour may be an increase of interest among biologists in this section of their domain, and a great accession to the number of those investigators who devote their energies to actual experiments in this new field.

For it must be confessed that it is a new field. It has been opened up in very gradual stages: fitful and sporadic experiments on the constitution of embryonic tissues in the seventeenth century, a gradual growth of knowledge about the chemical composition of eggs in the eighteenth, a big increase of activity in the early nineteenth; d'lTxiug which appear the first observations on the physico-chemical changes taking place in the embryo during its development, and then in our own time a mass of very widely scattered work bringing the subject up to the "obstetrical" stage. Such a work as this, in my opinion, should not be compared with laboratory experiments in a derogatory sense, for, while it is true that facts are the ultimate court of appeal in any scientific discussion, yet at the same time the number of investigators has grown to such extraordinary proportions in this century that some danger exists lest we should be so busily engaged in accumulating new facts as to be left with no time at all to devote any thought to those we have already. Classification, indexing, and maturer consideration about the facts we actually possess are at least as great a need at the present moment as the invention of new facts. "Everyone must realise", says Eugenio Rignano, "how much this theoretical elaboration, performed by means of analyses and comparisons, of generalisations and hypotheses controlled and verified by the correspondence of facts with the results of the reasoning, is useful and necessary if one wishes to reach a progressive systematisation and an ever more synthetic vision of the confused mass of facts which experimentalists pour daily in a continuous stream into the scientific market."

My predecessors in this work have been few in number. The volumes of Haller's, Buffon's, and Milne-Edwards' great treatises, in which they deal with the phenomena of generation, contain as much information as was available up to 1863, but this is purely of historical interest to us. In 1885, W. Preyer, Professor of Physiology at Jena, published his Spezielle Physiologie des Embryo, which still remains a most valuable review, and indeed, even to-day, is the only existing book specially devoted to embryonic physiology. The present century has produced only three books which even touch upon my subject, namely, T. B. Robertson's Chemical Basis of Growth and Senescence, F. H. A. Marshall's Physiology of Reproduction and E. Faure-Fremiet's La Cinetique du Developpement. The first of these was admittedly written to support a particular theory, and in any case says comparatively little about physico-chemical embryology. The second and the third deal with it only as a constituent part of a much wider field. In Marshall's case, the whole array of facts relating to oestrus and breeding, fertilisation and fertility, lactation and sex determination, have to be dealt with, and only three chapters out of sixteen are devoted to the subject of this book. The first of these is contributed by W. Cramer, and covers the biochemistry of the sexual organs, including the unfertiUsed egg ; the second, which deals with foetal nutrition and the placenta, is by J. Lochhead ; and the third, by these two investigators together, is concerned with changes in the maternal organism during pregnancy. Admirable as these chapters are, they are now rather out of date. Moreover, though one or two corners of the field I have before me were covered in Marshall's book, it was from a quite different standpoint.

Faure-Fremiet's work is exactly analogous; it deals with physicochemical embryology only, as it were, in passing. The relevant discussion takes up only two chapters out of seven ; the rest are occupied with tissue culture, growth of protozoal populations, and general cytology. His book covers, it might be said, the third and fourth corners : all the main expanse of the field remains.

Thus neither of these books deals with physico-chemical embryology in an exhaustive and comprehensive fashion, treating it as, in my view, it ought to be treated, with the thoroughness which is deserved by a new branch of natural knowledge. Inseparable, however, from thoroughness of treatment is the submergence of the parts of more general interest under a mass of detail, and it may be well therefore, to mention now what sections of the book could be said to be most valuable to any student of general biology. Part i comes in this class, and of Part iii, the middle portion of Section i, all of Sections 2, 3, and 5, thelatter half of Section 7, Sections 8, 9 (especially the end), 11, possibly 18, and finally the Epilegomena.

For my models in the preparation of this book, if it is permissible to name them, I have taken, Growth and Form by d'Arcy Thompson, surely the most scholarly work produced by a biologist in our time, and The Physiology of Reproduction by F. H. A. Marshall, already mentioned, which showed to all successors, in my opinion, how a colossal array of facts can be welded together into an absorbing and readable book, I am conscious that I shall not attain the level of these classics of modern biology, but then

.... Pauci, quos aequus amavit Jupiter, aut ardens evexit ad aethera virtus.

The progress of any branch of natural knowledge can be best described as a continual pilgrimage towards the quantitative. QuaUties can never be altogether left out of account and this is what makes it impossible for science to achieve its end with absolute finality. Yet an association with the probably unattainable is common to all the great types of man's activity. But "Fuyez toujours les a peu pres", as O. W. Holmes used to put it, is a proper maxim for the scientific mind, and whatever this book can do towards making embryology an exact science will be its final justification.

Cite this page: Hill, M.A. (2020, July 13) Embryology Book - Chemical embryology 1 (1900). Retrieved from

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