The Mechanism of Life.
by Stephane Leduc.
PREFACE
Professor Leduc"s _Theorie Physico-chimique de la Vie et Generations Spontanees_ has excited a good deal of attention, and not a little opposition, on the Continent. As recently as 1907 the Academie des Sciences excluded from its _Comptes Rendus_ the report of these experimental researches on diffusion and osmosis, because it touched too closely on the burning question of spontaneous generation.
As the author points out, Lamarck"s early evolutionary hypothesis was killed by opposition and neglect, and had to be reborn in England before it obtained universal acceptance as the Darwinian Theory. Not unnaturally, therefore, he turns for an appreciation of his work to the free air and wide horizon of the English-speaking countries.
He has ent.i.tled his book "The Mechanism of Life," since however little we may know of the origin of life, we may yet hope to get a glimpse of the machinery, and perhaps even hear the whirr of the wheels in Nature"s workshop. The subject is of entrancing interest to the biologist and the physician, quite apart from its bearing on the question of spontaneous generation. Whatever view may be entertained by the different schools of thought as to the nature and significance of life, all alike will welcome this new and important contribution to our knowledge of the mechanism by which Nature constructs the bewildering variety of her forms.
There is, I think, no more wonderful and illuminating spectacle than that of an osmotic growth,--a crude lump of brute inanimate matter germinating before our very eyes, putting forth bud and stem and root and branch and leaf and fruit, with no stimulus from germ or seed, without even {viii} the presence of organic matter. For these mineral growths are not mere crystallizations as many suppose; they increase by intussusception and not by accretion. They exhibit the phenomena of circulation and respiration, and a crude sort of reproduction by budding; they have a period of vigorous youthful growth, of old age, of death and of decay. They imitate the forms, the colour, the texture, and even the microscopical structure of organic growth so closely as to deceive the very elect. When we find, moreover, that the processes of nutrition are carried on in these osmotic productions just as in living beings, that an injury to an osmotic growth is repaired by the coagulation of its internal sap, and that it is able to perform periodic movements just as an animal or a plant, we are at a loss to define any line of separation between these mineral forms and those of organic life.
In the present volume the author has collected all the data necessary for a complete survey of the mechanism of life, which consists essentially of those phenomena which are exhibited at the contact of solutions of different degrees of concentration. Whatever may be the verdict as to the author"s case for spontaneous generation, all will agree that the book is a most brilliant and stimulating study, founded on the personal investigation of a born experimenter.
The present volume is a translation of Dr. Leduc"s French edition, but it is more than this, the work has been translated, revised and corrected, and in many places re-written, by the author"s own hand. I am responsible only for the English form of the treatise, and can but regret that I have been able to reproduce so imperfectly the charm of the original.
W. DEANE BUTCHER.
EALING.
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PREFACE TO THE ENGLISH EDITION
C"est par l"initiative du Dr. Deane Butcher que cette ouvrage est presente aux lecteurs anglais, a la race qui a dote l"humanite de tant de decouvertes originales, geniales et d"une portee tres generale.
Comme un etre vivant, une idee exige pour naitre et se developper le germe et le milieu de developpement. Il est indeniable que le peuple anglo-americain const.i.tue un milieu particulierement favorable a la naissance et au developpement des idees nouvelles.
Pendant notre collaboration le Dr. Deane Butcher a ete un critique judicieux et eclaire, tous les changements dans l"edition anglaise sont dus a ses observations. Il s"est a.s.simile l"ouvrage pour le traduire, et dans beaucoup de parties, il a mis plus de clarte et de concision qu"il n"y en avait dans le texte original.
STePHANE LEDUC.
NANTES, 1911.
INTRODUCTION
Life was formerly regarded as a phenomenon entirely separated from the other phenomena of Nature, and even up to the present time Science has proved wholly unable to give a definition of Life; evolution, nutrition, sensibility, growth, organization, none of these, not even the faculty of reproduction, is the exclusive appanage of life.
Living things are made of the same chemical elements as minerals; a living being is the arena of the same physical forces as those which affect the inorganic world.
Life is difficult to define because it differs from one living being to another; the life of a man is not that of a polyp or of a plant, and if we find it impossible to discover the line which separates life from the other phenomena of Nature, it is in fact because no such line of demarcation exists--the pa.s.sage from animate to inanimate is gradual and insensible.
The step between a stalagmite and a polyp is less than that between a polyp and a man, and even the trained biologist is often at a loss to determine whether a given borderland form is the result of life, or of the inanimate forces of the mineral world.
A living being is a transformer of matter and energy--both matter and energy being uncreateable and indestructible, i.e. invariable in quant.i.ty.
A living being is only a current of matter and of energy, both of which change from moment to moment while pa.s.sing through the organism.
That which const.i.tutes a living being is its form; for a living thing is born, develops, and dies with the form and structure of its organism. This ephemeral nature of the living being, which perishes with the destruction of its form, is in {xiv} marked contrast to the perennial character of the matter and the energy which circulate within it.
The elementary phenomenon of life is the contact between an alimentary liquid and a cell. For the essential phenomenon of life is nutrition, and in order to be a.s.similated all the elements of an organism must be brought into a state of solution. Hence the study of life may be best begun by the study of those physico-chemical phenomena which result from the contact of two different liquids. Biology is thus but a branch of the physico-chemistry of liquids; it includes the study of electrolytic and colloidal solutions, and of the molecular forces brought into play by solution, osmosis, diffusion, cohesion, and crystallization.
In this volume I have endeavoured to give as much of the science of energetics as can be treated without the use of mathematical formulae; the conception of entropy and Carnot"s law of thermodynamics are also discussed.
The phenomena of catalysis and of diastatic fermentation have for the first time been brought under the general laws of energetics. This I have done by showing that catalysis is only one instance of the general law of the transformation of potential into kinetic energy, viz. by the intervention of a foreign exciting and stimulating energy which may be infinitely smaller than the energy it transforms. This conception brings life into line with other catalytic actions, and shows us a living being as a store of potential energy, to be set free by an external stimulus which may also excite sensation.
In a subsequent chapter I have dealt with the rise of Synthetic Biology, whose history and methods I have described. It is only of late that the progress of physico-chemical science has enabled us to enter into this field of research, the final one in the evolution of biological science.
The present work contains some of the earliest results of this synthetic biology. We shall see how it is possible by the mere diffusion of liquids to obtain forms which imitate with the greatest accuracy not only the ordinary cellular tissues, but the more complicated striated structures, such as muscle and mother-of-pearl. We shall also see how it is {xv} possible by simple liquid diffusion to reproduce in ordered and regular succession complicated movements like those observed in the karyokinesis of the living cell.
The essential character of the living being is its Form. This is the only characteristic which it retains during the whole of its existence, with which it is born, which causes its development, and disappears with its death. The task of synthetic biology is the recognition of those physico-chemical forces and conditions which can produce forms and structures a.n.a.logous to those of living beings. This is the subject of the chapter on Morphogenesis.
The last chapter deals with the doctrine of Evolution. The chain of life is of necessity a continuous one, from the mineral at one end to the most complicated organism at the other. We cannot allow that it is broken at any point, or that there is a link missing between animate and inanimate nature. Hence the theory of evolution necessarily admits the physico-chemical nature of life and the fact of spontaneous generation.
Only thus can the evolutionary theory become a rational one, a stimulating and fertile inspirer of research. We seek for the physico-chemical forces which produce forms and structures a.n.a.logous to those of living beings, and phenomena a.n.a.logous to those of life. We study the alterations in environment which modify these forms, and we seek in the past history of our planet for those natural phenomena which have brought these physico-chemical forces into play. In this way we may find the road which will, we hope, lead some day to the discovery of the origin and the evolution of life upon the earth.
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THE MECHANISM OF LIFE
CHAPTER I
LIFE AND LIVING BEINGS
Primitive man distinguished but two kinds of bodies in nature, those which were motionless and those which were animated. Movement was for him the expression of life. The stream, the wind, the waves, all were alive, and each was endowed with all the attributes of life--will, sentiment, and pa.s.sion. Ancient Greek mythology is but the poetic expression of this primitive conception.
In the evolution of the intelligence, as in that of the body, the development of the individual is but a repet.i.tion of the development of the race. Even now children attribute life to everything that moves. For them a little bird still lives in the inside of a watch, and produces the tick-tick of the wheels. In modern times, however, we have learnt that everything in nature moves, so that motion of itself cannot be considered as the characteristic of life.
Herac.l.i.tus aptly compares life to a flame. Aristotle says, "Life is nutrition, growth, and decay,--having for its cause a principle which has its end in itself, namely [Greek: entelecheia]." This principle is itself in need of definition, and Aristotle only subst.i.tutes one unknown epithet for another.
Bichat defined life as the ensemble of the functions which resist death.
This is to define life in terms of death,--but death is but the end of life, and cannot be defined without first defining life. Claude Bernard rejects all definition of life as insufficient, and incompatible with experimental science. {2}
Some modern physiologists regard sensibility, others irritability, as the characteristic of life, and define life as the faculty of responding, by some sort of change, to an external stimulus. As in the case of movement, we have found by more attentive observation that this faculty also is universal in nature. There is no action without reaction; an elastic body repels the body that strikes it. Every object in nature dilates with heat, contracts with cold, and is modified by the light which it absorbs.
Everything in nature responds to exterior action by a change, and hence this faculty cannot be the characteristic of life.