BOOK II.
THE DOCTRINE OF ENERGY AND THE LIVING WORLD.
Summary: General Ideas of Life.—Elementary Life.—Chapter I. Energy in General.—Chapter II. Energy in Biology.—Chapter III. Alimentary Energetics.
GENERAL IDEAS OF LIFE. ELEMENTARY LIFE.
Life is the Sum-total of the Phenomena Common to all Living Beings. Elementary Life.—Living beings differ more in form and configuration than in their manner of being. They are distinguished more by their anatomy than by their physiology. There are, in fact, phenomena common to all, from the highest to the lowest. This is because there is that similar or identical foundation, that quid commune which has enabled us to apply to them the common name of “living beings.” Claude Bernard gave to this sum-total of manifestations common to all (nutrition, reproduction) the name of elementary life. To him general physiology was the study of elementary life; the two expressions were equivalent, and they were equivalent to a longer formula which the illustrious biologist has given as a title to one of his most celebrated works—The Study of the Phenomena Common to all Living Beings, Animals, and Plants. From this point of view each being is distinguished from another being as a given individual and as a particular species; but all are in some way alike and thus resemble one another: common life, elementary life, the essential phenomena of life; it is life itself.[4]
The manifestations of life may therefore be regarded from the point of view of what is most general among them. As we go down the scale of anatomical organization, as we pass from apparatus (circulatory, digestive, respiratory, nervous) to the organs which compose them, from the organs to the tissues, and finally from the tissues to the anatomical elements or cells of which they are formed, we approach that common, physiological dynamism which is elementary life, but we do not actually reach it. The cell, the anatomical element, is still a complicated structure. The elementary fact is further from us and lower down. It is in the living matter, in the molecule of this matter, and there we must seek it.
Galen gave in days gone by as the object of researches on life, the knowledge of the use of the different organs of the animal machine; “de usu partium.” Later, Bichat assigned to them as their end the determination of the properties of tissues. Modern anatomists and zoologists try to reach the constituent element of these tissue—the cell. Their dream is to construct a cellular physiology, a physiological cytology; but we must go further than that.
General Physiology, Cellular Physiology, the Energetics of Living Beings.—General physiology, as was taught by Pflüger and his school, claims to go deeper down than the apparatus, or the organ, or even the cell. As in the case of physics, general physiology endeavours to reach, and really does in many cases reach, as far as the molecule. It is not cellular, it is molecular. Already, in fact, the efforts of modern science have succeeded in penetrating into the most general phenomena of the living being—those attributable to living matter, or, to speak more clearly, those which result from the play of the universal laws of matter at work in this particular medium which is the organized being.
Robert Mayer and Helmholtz have the honour of having set physiology in the right road. They founded the energetics of living beings—i.e., they regarded the phenomena of life from the point of view of energy, which is the factor of all the phenomena of the universe.
CHAPTER I.
ENERGY IN GENERAL.
Origin of the Idea of Energy.—The Phenomena of Nature bring into play only two Elements, Matter and Energy.—§ 1. Matter.—§ 2. Energy.—§ 3. Mechanical Energy.—§ 4. Thermal Energy.—§ 5. Chemical Energy.—§ 6. The Transformations of Energy.—§ 7. The Principles of Energetics.—The Principle of the Conservation of Energy.—§ 8. Carnot’s Principle.—The Degradation of Energy.