The origin of life : its physical basis and definition

Preface

In presenting this work to the judgment of my critics, as the result in part of my studies for some years past, in some respects in outline whilst in others in detail, and more so perhaps than it was my intention at first to make it, two points should be borne in mind. In the first place, it is intended that the chapters which deal with phosphorescence may with advantage be omitted by those who are not particularly interested in such matters, since they may tend to divert the attention from the real points at issue, if the mind is not specially familiar with physical conceptions. The reader who does not wish to be burdened with detail is therefore recommended to omit them, at any rate on the first reading, if the book should prove of sufficient interest to demand his perusal for a second time. Those chapters of a purely physical and perhaps somewhat technical nature, which he thus may think it worth his while to pass over, have been introduced to illustrate the way in which the phenomenon which I have called physical metabolism admits of comparison with the highly

VI

PREFACE complex biological effects in bringing out the essential features of the work. If therefore he passes over these he will find in the other chapters a resume of the results which they contain. In the second place, it must not be supposed that the problem of the origin of life has been solved to the satisfaction of all parties or of any, even if a clue to its solution may be claimed in a suggestive form.

Since the days of the great controversy in which Tyndall and Huxley took so prominent a part, the interest in the question of spontaneous generation has scarcely surpassed, nor in some respects does it appear to have equalled, the enthusiasm which these experiments, whatever their ultimate bearing on the question, have aroused.

Although it is not the object of this book to lend support to the doctrine of abiogenesis, or the development, at the present day, of living from absolutely non-living matter, the more hopeful, though as it must be admitted less gratifying, view to take, is that we have arrived at a method of structural organic synthesis of artificial cells, which, if it does not give us natural organic life such as we see existing around us, gives us at least something which admits of being placed in the gap, or, as it might preferably be called, the borderland, between living and dead matter, as familiarly understood.

Those who will approach the subject will, it is hoped, approach it with an open mind, and re-

PREFACE

Vll member also that great as has been the progress of science generally in the nineteenth century, we are after all merely at the dawn, so to speak, of that knowledge which is beginning to appear before us : that, in fact, in 2,500 years to come — if it is not too far ahead to think of, and it certainly ought not to be if we are to face the question in the proper light — people will doubtless look back to the work of this century in much the same fashion as we too are wont to look back, though it is to be hoped not down, upon the great efforts and marvellous speculations of the Greek mind of 2,500 years ago, in its brilliant attempts to unravel the problem which has puzzled humanity for ages : a problem which doubtless will continue to puzzle it to a considerable extent for many days to come. The why and the wherefore we may ask, but get no answer to ; the how is our only consolation : and even in that do we need the most careful steering to avoid the pitfalls and precipices of error.

One word more I feel should preface the introduction to this book, and that is to express my indebtedness to the editor of the Fortnightly Review for his kindness in permitting me to reproduce here part of an article which has appeared in his Review, and to state also, how much the interest which this subject has evoked in England and in America is due to him and others mentioned in the text.

JOHN BUTLER BURKE.

Cambridge,

January, 1906.

Chapter I Introduction — The Nature Op The Problem

PAGE

Plan of the book— Relationship of natural phenomena — The continuity of vital processes — Historical— Aristotle, &c. —

Life as a series of molecular changes — The gradual scale from the more complex to the simpler forms of molecular aggregation' — Luminosity and metabolism — Phosphorescence and the simpler forms of life — Physical evidence of simple metabolism in fluorescent and in radio-active bodies • — Pfliiger’s theory — Experiments with radium and bouillon — Borderland between mineral and vegetable kingdoms —

The dawn of life 1

Chapter II The Continuity Of Vital Processes

The properties of living matter — Life as conditioned by moisture and temperature — Metabolism and the intussusception of new matter or integration ; and waste or disintegration by oxidation — The cyclic process — Chemical composition and protoplasm — Life and organisation — Bastian on protoplasm — Stimulation — Work — Herbert Spencer’s definition of life — Fechner’s views — The continuity of the animate and inanimate when clearly defined— Three stages that science has to pass : empirical, classificatory, theoretical 25

Chapter III Classification Of Living Tvpes

Reasons for extending the meaning of the word life to include a wider class of phenomena — Sciences not divided into watertight compartments, but their division largely arbitrary — Survival of living proteid— Definition of life — Life-stuff — Manner in which it may have at first arisen — Continuity of organic and inorganic matter — Biogenesis carried to its

X logical extreme — Haeckel and biogenesis — Cyclic process the test of life in the higher forms of matter — Whether a cell-wall is necessary in ultra-microscopic germs — Metabolic combination of two opposite processes — How they are effected — F ormation of molecular aggregates — Many crystals may be fossilised remains of living matter — Classification should not be between organic and inorganic but between active and inert matter

Chapter IV The Correlation Of Vital Phenomena

The object in view — Results outcome in part of researches originally started as to the phenomena of phosphorescence — Object to arrive at dynamical explanations — Luminosity result of metabolic actions, of a building up and breaking down of molecules — Fluorescence and phosphorescence — Luminosity of gases when an electric discharge passes through them — Theory of large chains of molecules — Fluorescence and absorption — Inferences to be drawn from these — Luminous and non-luminous states of matter two different states — Catalytic actions — Enzymes and nuclei— Stable and unstable groups of molecules — Atoms may be elementary cells — Biogenesis carried to its logical extreme — Huxley’s scientific faith — Views of Johannes Muller—1 The unity and plurality in "Nature everywhere combined, and constitute its continuity

Chapter V

This correlation of Vital Phenomena opens up a new perspective — Life in its primitive state must have been different from anything now observed in Nature — According to Clerk Maxwell the number of atoms in the cell is not sufficient to account for its immense potentiality — This potentiality, with all its varieties, probably the result of perturbations in the particular motion which constitutes the principle of vital activity — How it may have arisen — Natural as distinct from artificial life — Radio-activity of living bodies, plants, and animals — Experiments of Tommasina — Origin of primitive radio-active bodies lost in same obscurity as that of primitive life

Chapter VI Experiments With Radium And Culture Media

Experiments with glycerine and liquid air— Dr. Gladstone’s glycerine crystals — Culture produced by radium salts in xi gelatin bouillon— Other globular bodies produced by gum and gelatin— Reasons for supposing radiobes are not bacteria — Negative experiments with cyanogen — Pfliiger’s theory — Nature of the cyanogen molecules and of the radium molecules— Dubois’ vacuolides not radiobes — Sachs’s theory of colloid bodies : that they are crystals asymmetrically arranged —Experiments of Leduc, Biitschli, and others — Discussion of Pasteur’s results and their bearing on the present experiments— Radiobes and primitive life 90

CHAPTER YII

ON ARTIFICIAL CELLS AND ARTIFICIAL LIFE

Nature of the bodies produced by radium — von Schrdn’s petroblasts — Apparent life in young crystals — Bodies observed by Quincke — Foam-cells — Cellular protoplasm, how it may have been formed — Sir William Ramsay’s helium bubbles — How these may be formed and what their behaviour would be — M. Raphael Dubois and mineral cultures or vacuolides produced by barium salts — Experiments with barium and other salts — The peculiar nature of uranium cultures— Whether it is radio-activity that produces the effect and in what way — It is not the emitted rays a, /3, or y ; but probably slow-moving rays — Structure of such artificial cells — Their sensitiveness to electrical and chemical stimuli — Their Parthenogenesis — Work of Loeb — Mode of subdivision probably similar 113

CHAPTER YIII

ON THE STRUCTURE OF CELLS, NATURAL AND ARTIFICIAL, AND THE SOURCE OF THE ENERGY OF VITAL FLUX

Distinction between artificial and natural life — Morphology of cells — Vital process essentially a metabolism — Complexity of cell structure and potentiality of cell — The vital process as distinct from complexity of structure — The nucleus and Karyokinesis — Max Verworn cn structure as result of metabolism — Whether his views may not be modified in the light of more recent ideas of the nature of solid and liquid bodies — Difficulties in studying structure of living cell — Cellular structure imparted by reagents — The ultimate or nth nucleus — Its probable nature, an aggregate of electrons like a radio-active element — Internal energy of living matter thus stored up in the aether — This may fit in as a physical and dynamical explanation of Sir Oliver Lodge’s immaterial source of energy in living organisms, thus apparently independent of material connections, but really subject to the universal law of the conservation of Energy 132

Xll

CHAPTER IX

THE NUCLEUS AS A SOURCE OF ENERGY

PAGE

Nucleus a* a source of energy— Possible mode of reconciliation between opposite schools of Haeckel and Lodge — Bio-elements— Altmann’s bioplasts — Dr. Charlton Bastian and the transmutation of species — Life-activity and radio-activity — Richter and Preyer’s cosmoza — Bathybius and precipitates — The problem of the origin of life runs parallel with that of the origin of matter „ 153

CHAPTER X

THE DESCENT OF LIVING PROTOPLASM

Artificial cells in their relation to the mode in whi'ch life first made its appearance — Criticisms as to the nature of these cells — Preyer’s theory — The small chance of the particular aggregations constituting a living cell being formed — Experiments with cyanogen and electric discharge — Probable structure of Haeckel’s Monera — Fresh speculation in their relation to biogenesis 172

CHAPTER XI

Three states of electronic aggregation — Spontaneous generation a problem like that of perpetual motion cannot be demonstrated— Views of Pasteur and Weismann — Objections to Pasteur’s results — Views of Bastian — J. Arthur Thomson — Haeckel — Bastian’s heterogenesis — Method of filtration — Japp’s views on asymmetric structures — Asymmetric structure of biogen — Origin of asymmetric structure as profound as that of life — Karl Pearson and FitzGerald on climate as a factor in producing asymmetry 191

CHAPTER XII

Two opposing principles in vital processes ; the constructive and the destructive — Mode in which metabolism is kept up in the cell in consequence of the electrical and radio-active properties of the nucleus— Artificial cells merely models, but yet give a clue to the nature of the mechanism in natural ones — Biogen hereditary substance — Nature of this substance — Biogen the transition stage between free electricity and condensed electricity or atomic matter — Astronomical analogue — Constituents of protoplasm the lightest elements — Bearing of this on the origin of protoplasm —

Two kinds of biogens 213 xiii

CHAPTER XIII

PAGE

The phenomenon of fluorescence — Discovered by Herschel— Change of refrangibility discovered by Stokes — Work of Lommel — Change of absorption— Description of experiments on this — Views of C. E. Guillaume and A. Cotton- Negative results — The experiments of Nichols and Merritt — Relation between absorption and the intensity of fluorescence— Inference to be drawn from these observations and the change of refrangibility, the fluorescence being independent of the period of the exciting light — Fluorescence a building up and breaking down of molecules— Physical metabolism 232

CHAPTER XIV

RADIATION AND MOLECULAR AGGREGATION

Summarily the result of association and dissociation — Or more or less complex molecular groups — Radiation from flames — Tyndall’s experiments on the emissive and absorptive powers of gases —Spectra of oxygen — Repulsion between spheres of molecular dimensions whilst radiating intensely — How aggregates may preserve their identity — Catalytic action — Effect of glycerine and gelatin on aggregation in fluorescent bodies 251

CHAPTER XV

ON THE FORMATION OF AGGREGATES OF LARGE MOLECULES

The effect of infra-red rays — Stokes’ law reversed, or calorescence — The function of a nucleus in phosphorescent bodies — The effect of surface tension on aggregation — Influence of films — Chemical reaction in high vacua 266

CHAPTER XVI

PHOSPHORESCENCE AND MOLECULAR AGGREGATION

Phosphorescence and catalytic action — Effect of molecular concentrations on freedom of corpuscles — Dependence of phosphorescence upon free-paths and velocity of corpuscles — Existence of separate phosphorescent molecules in liquids, and of separate active molecules in luminous gases — That separate large molecules exist in flames — The process of catalysis and metabolism once more 278

XIV

CHAPTER XVII

RADIO-ACTIVITY AND PHOSPHORESCENCE

PAGE

Molecular theory of phosphorescence and of radio-activity— Analogy between phosphorescent molecules and those of radio-active emanation from thorium and radium compounds— Model of radio-active and phosphorescent molecules— Model of positive ion — The electric theory of matter 292

CHAPTER XVIII

MODELS OP POSITIVE ION OR ATOMIC NUCLEUS

Fluorescence of monatomic gases — Effect of specific inductive capacity on molecular aggregation — Difficulties in the kinetic theory — Nature of positive nucleus — Effect of approach of corpuscles on motion in nucleus — Balmer’s law — Ramage’s observations — Transmutation of the elements of same series — Aggregations produced by pressure — Models of molecules in phosphorescent gases and in emanations 308

CHAPTER XIX

MATTER AND “ MIND-STUFF ”

Conclusions — Resume of what has been said — Biogen is matter in process of becoming or being transformed from free electricity into condensed electricity, called atoms — Universal nature of physical metabolism — Matter a mode of motion — Motion a complex perception or mode of thought — Two modes of thought, our own minds and matter are concomitant^— Difficulty solved by Idealism — Berkeley and Hume — Their respective positions — Mind-stuff, how reconciled with Idealism — The permanent source of possible sensation . . 332

LIST OF ILLUSTRATIONS

Test-tube containing Radium or other Salt, for Purpose of

Sterilisation 92

Test-tubes showing various Cultures • . 92

Developments during First Week 98

After a Fortnight 100

Plates I., II., III., of Developments 100, 102

Leduc’s Cells 104

Lehmann’s Liquid Crystals 106

Nine Stages of Development of Radiobes . 108, 110, 112, 112(a), 112(6)

Lehmann Crystals 118, 120

Sir Wrn. Ramsay’s Cells and their Effect on Nuclei . . 120 (a) to (e)

M. Dubois’ Vacuolides 122

Deflection of Radiation in a Magnetic Field and other Properties

of a-, ft-, y-Rays 126

Stoney’s Diagram illustrating the Periodic Law 227

Stokes’ Demonstration of his Law of Change of Refrangibility . 235

Method of Measuring Change of Absorption 239

Nichols and Merritt’s Curve for Absorption and Intensity of

Fluorescence 247

Phosphorescent Gas Experiments 285

Chapter I Introduction. — The Nature Of The Problem

Plan of the book — Relationship of natural phenomena — The continuity of vital processes — Historical — Aristotle, &c. — Life as a series of molecular changes — The gradual scale from the more complex to the simpler forms of molecular aggregation — Luminosity and metabolism — Phosphorescence and the simpler forms of life — Physical evidence of simple metabolism in fluorescent and in radio-active bodies — Pfliiger’s theory — Experiments with radium and bouillon — Borderland between mineral and vegetable kingdoms — The dawn of life.

The aspect of the question which it is the object of this essay to expound in as familiar and yet philosophic terms as the subject will itself admit of, is primarily twofold. That twofold aspect is that of actual knowledge and of speculation. For in its first origin as well as in its last end, life remains and doubtless for long ages, if not for ever, will remain a mystery to the intelligence of human beings. Between these two limits, however, there is much known and to be known. And the two means of attack may work together although

B quite independently, lest a false step on the part of the scout or guide should, to speak metaphorically, pull knowledge down or divert it from its true path of progress. This essay then is the embodiment of speculation and of experiment, the latter being the handmaid of that speculation that more than once it has pulled up and diverted in another course. Throughout, it is the author’s wish that the work should be, and present itself to those who follow the line of reasoning mapped out in it as being, an effort in the pursuit of an object one does not profess to have attained, nor perhaps hopes ever to attain, but only to pursue. If it has added a few steps, or even only one, towards the solution of the problem, that step will not have been taken altogether in vain.

Theory and experiment must go hand in hand, and much depends on one as much as on the other, not merely upon its accuracy but also upon its nature. Hundreds of experiments may be made, which, however, notwithstanding their refinement and accuracy, contribute little to the march of human progress in the right direction ; they may of course in ages count for much, but the chief thing is that the experiment should be of the right kind, and it is often desirable that as much time, if not even more time, should be spent in deciding upon the right thing to be done than in doing that thing itself. One bad theory is often worse than ten bad experiments, because even if these are properly carried out, they may yet, if based upon false notions, add little or nothing, if not to the store at least to the advancement of knowledge : and count almost for as little as the one bad experiment whether based upon theory or not.

Attention is therefore needed in the choice of the path to be pursued as well as in the pursuit itself. Now for our part we do not wish to affirm, nor strictly speaking even to suggest, that the theories herein hazarded and the experiments described to verify them, have been in all cases in the right direction ; what may be affirmed, however, is that some trouble has been taken in deciding on them. No doubt the same end may be reached by divers paths.

The subject is thus approached, if one may venture to approach it so, from a different standpoint from that which the biologist, trained as he would be in another frame of mind, would naturally have started from. It is attacked from the standpoint of a physicist who endeavours to disclose in many of the phenomena, perhaps more familiar to physicists than to biologists, the striking resemblance between many physical and biological effects.

The object of this book then is to indicate, and it is hoped also to prove, so far as proof is possible, the continuity of vital processes ; that the links between the organic and the inorganic, between living and dead matter form an unbroken and continuous chain, which connects biology with physics as closely as it unites the two with chemistry.

The doctrine of spontaneous generation was in the Middle Ages accepted as a fact : and those who may

B 2 affirm it now are not such heretics as might at first sight be imagined.

It was the accepted theory in Europe at an earlier period than the Middle Ages, and, in fact, for more than eighteen hundred years. Not till the seventeenth century does it appear to have been seriously questioned. Indeed, as Huxley reminds us, just two hundred and thirty-seven years ago a student, Francesco Redi, a native of the country which numbers amongst her sons so many illustrous names of the sixteenth and seventeenth centuries — whose studies have become associated for all time with the great work of laying the foundation of modern science — enunciated the hypothesis now known as biogenesis ; that all living matter has sprung from pre-existing living matter. “ The extreme simplicity of his experiments and the clearness of his arguments, gained for his views, and for their consequences, almost universal acceptance. He was a man of the widest knowledge and most versatile abilities, distinguished alike as scholar, poet, physician and naturalist. His work Esjoerienze intorno alia Generazione degV Insetti went through five editions in twenty years ” 1 : a record which in those days was considered quite exceptional. Now Father Needham, who was associated with Buffon, the great French naturalist, as a believer in what we should, at the present day, call abiogenesis, or the production of living from dead matter, produced experiments

1 Biogenesis and Abiogenesis — Discourses, Biological and Geological.

which seemed to refute Redi’s. The results of these, however, were uot accurately supposed to prove abiogenesis ; for Buffon assumed the existence of “ organic molecules ” of some substance possessing the inherent properties of life ; the molecules of this substance being indestructible, and in modern nomenclature it might be regarded as an element endowed with the potential properties of life.

But Needham and Buffon were encountered by the destructive facts brought forward again by an Italian, the Abbe Spallanzani, who repeated Needham’s experiments. He showed that if the tubes used in these experiments were subjected to the temperature of boiling water for three-quarters of an hour and the access of air eliminated by hermetically sealing the tubes, no sign of living forms or animalcules appeared.1 In these and all subsequent experiments — including those of Pasteur and of Tyndall as recently as thirty years ago — nothing was really proved : because when animalcules did appear the obvious explanation was that the sterilisation was imperfect ; whilst when they did not appear after heating the still more obvious retort was that the process of sterilisation destroyed not merely previously existing life ; but also the conditions by which life in ordinary circumstances could possibly have originated.

The only case which seems conclusive, then, is that when living forms arise which it could be proved would not have stood the temperature to which they had 1 See Huxley, loc. cit.

been previously subjected. Or when by repeated heating and cooling they can be made to disappear and reappear again. If those which appear after the first sterilisation when two substances are brought together are entirely different from any which had previously existed therein before sterilisation was carried out, there can be little doubt that spontaneous generation in some form had actually taken place, or at any rate heterogenesis, for which Dr. Charlton Bastian has fought so persistently and for so many years.

Of this we propose to discourse in this book ; whilst the results we have arrived at give us no small reason to believe that the continuity of living and not living substance, as familiarly understood, is a matter which cannot be passed over without pause.

The ancient philosophers like Aristotle believed that motion constituted life. And in regarding Life as mode of Motion, however inadequate that idea (in its ultimate simplicity) may really be, we have been guided by a somewhat similar conception, the notion kept before our mind being, not motion in all its simplicity, for the mere state of motion does not constitute life, but motion in some particular form. Life being, so to speak, a specialised motion, and all its manifestations accompanied by a particular kind, or kinds, of molecular interchange. It is a series of fermentations and thus also a series of catalytic actions and interactions, a catalytic action being a molecular change or series of chemical changes, brought about by the presence of some substance which apparently takes no part in the chemical reactions, but only acts as the medium by which the process is set going and also carried out. This in itself, however, does not constitute the whole nature of the mechanism designated by vitality. The mechanical actions, if they may be so called, are throughout of the nature of a building up and breaking down of complex molecular aggregations ; and essentially of a dynamically unstable kind. This process of building up and of breaking down of such molecules is called metabolism. It is not confined to ordinary physiological processes, but in a gradually simplifying scale, it is to be found even in many purely chemical and physical phenomena. It can be detected even in some of the processes as manifested in the phenomena of radio-activity.

Nay, it is not confined to these, for even in those phenomena in which we should least expect it, it appears to be the mechanism by which radiation in many cases, as, for instance, luminosity is almost invariably accomplished. That the luminosity of flames and that of phosphorescent and fluorescent bodies are of this nature, due to the building up and breaking down of such highly complex molecular agglomerations, though much simpler than those of proteids, there is ample reason from experimental evidence to think. In other words, that these too are of the nature, and come under the class of metabolic action, although, of course, it is simpler than that which takes part in living processes as familiarly understood. Still there does exist the gradual simplification of such interaction in Nature’s scale of being ; and although we cannot go so far as to assert that luminous bodies like the flame of the candle, for instance, or an incandescent mantle, can be classified with living things, in their most elementary states, we may say that they at least partake in the process of metabolism ; and if metabolism were the whole and the only thing that constituted vital action, they would, of course, be entitled to be included with such things. Flames, phosphorescent bodies, and probably luminous bodies generally, would thus come within the realm of biology, or, more accurately speaking, constitute a science in themselves such as Bio-Physics.

We must, however, before accepting this extension or this fusion of the two sciences, be careful that we are not altogether over sanguine. For does metabolism constitute the whole of vital actions, or should vital processes be confined to metabolic change ? This is a question which will form the subject, or the subjects, of discussion in the chapters which are to follow.

The notion that all things are alive, and differ in this respect only in degree, is thus fraught, it should appear, with many advantages, and yet not without its disadvantages. We shall see then, with all due caution and reserve, which the subject naturally demands, how far the idea permits of an extension, if of an extension it admits at all.

It' is of interest to note that the notion that luminous bodies are in some elementary sense alive was quite common to the ancients. Thus Hippocrates thought that flames were living things ; whilst the idea that the sun was the source not merely of light but of life, and that it is itself alive, is of very ancient origin ; as ancient as that of the fire-worshippers themselves.

And, further back, Sfirruta, the author of probably the earliest Indian Manuscript upon the art of healing, the Yajueveda, regarded all moving bodies as living, and those at rest as dead.1 But these fantastic notions were never developed into any consistent and coherent whole, no systematic observations or speculations framed before Aristotle took up the study of the question, and it is all the more remarkable that with him it was allowed to drop. Some of his reflections in these matters, as in almost everything he dealt with, are remarkably astute. As the theory of the struggle for existence and survival of the fittest was most surprisingly taught by Empedocles (b. 504 B.C.), so Aristotle (384 — 322 b.c.) in his work, however erroneous in many ways, recorded a great number of interesting and for the time being important facts, and believed in the spontaneous development of life ; but he also thought that eels and frogs were evolved by spontaneous generation. Anaximander believed in what was the equivalent of the nebular theory and he also assigned to life an origin in inorganic materials of primitive or pristine mud.

Through the minute study of living forms since the time of Harvey it has been generally assumed that the barrier between animate and inanimate

1 See Vernon’s General Principles of Physiology, translated by Frederick S. Lee.

io THE ORIGIN OF LIFE

nature is great and insurmountable, and still more so during the close of the nineteenth century has it been supposed, not without good reasons, that biology was sharply marked off from the a-biological sciences. The boundary between living and dead matter was supposed to be adequately defined, whereas we think it now appears it can no more be laid down than that between biology and psychology, or biology and sociology. Between biology and physics it seems to be indefinable. When we bear in mind the gradual and continued simplification as we descend from the most complex forms to the simplest atoms, it cannot fail to attract the attention of the acute observer that so also this continual dropping off of properties means something. That the process is in the limit continuous. This is the doctrine we propose to consider, and which we may in the end be forced, whether willingly or unwillingly, to accept as the most consistent and scientific one.