Читать книгу The Mechanism of Life - Stéphane Leduc - Страница 3

Table of Contents

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 passage 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 quantity. A living being is only a current of matter and of energy, both of which change from moment to moment while passing through the organism.

That which constitutes 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 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 assimilated 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 formulæ; 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 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 analogous 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 analogous to those of living beings, and phenomena analogous 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.