COST OF FUEL AND FOOD

45

human beings for mechanical work rather than machinery. The answer is very easy; because of the cost of food in comparison with fuel. A steam engine will work all day at a cost for its fuel of twenty cents; the food of two horses, the equivalent of the machine, costs $2.00; and the food of twenty-four men, required to perform the same work, costs $10.00. Hence, as Donders has shown, the animal body can never successfully compete with the steam engine, and "the worst use to make of a man is to employ him exclusively in mechanical work, a statement which harmonizes with the increased introduction of machinery in our advancing civilization."

If we should allow any humanitarian influence a place at all in this consideration, we should have to remember also that if we divert all the force in the body to mechanical work, there is none left for mental work. The force of the body is of course pretty much a fixed quantity, just as it is for a machine, depending largely upon its original construction, as determined by heredity. We cannot use all the power of a machine for a special purpose, say to saw a log, and have enough left to turn a mill-stone. So with very few exceptions hard muscular workers achieve no eminence in intellectual life. Stallions whose force is to be used in reproduction are kept idle in the stalls.

The body of man is built up of cells (protoplasm), which are, in turn, composed of atoms or molecules, whose arrangement (transmitted by heredity and modified by external conditions) determines the special action or use. Or, as Goethe has put it: "Nicht allein das angeborene, auch das Erworbene ist der Mensch." (Man is not alone what he inherits; he is also what he acquires.) The action of protoplasm, though sometimes apparently, is never really spontaneous. The cells are called into action by stimulus, which, so far as we can trace it, always pro

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PHYSIOLOGICAL, A PHYSICAL FORCE.

ceeds from without. The various phenomena of life are principally manifestations of reflex action. In simple bodies (individual masses of protoplasm) the outside stimulus is conveyed from atom to atom, like chemical force in gunpowder, from grain to grain. In complex bodies the stimulus is carried along definite trains (nervestrands) to special destinations. If a muscle contract, it contracts in obedience to stimulus carried to it by a motor nerve. The stimulus conveyed along the nerve has its development in a nerve-center (ganglion). The stimulus experienced in the nerve-center is in turn derived from a sensitive nerve. The sensitive nerve transmits an impression received upon a sensory surface (skin, mucous membrane, gland, etc.). Even the most complex manifestations of the brain fall under the same category. Socalled voluntary movements are only the final responses to impressions made upon the special senses at the time or in the past (memory). The highest expressions of the intellect of man may be resolved into the more perfect transmutations of outside forces by machinery made more perfect by original construction (heredity), or made more perfect by labor, (education).

Thus :

Physiological is Correlative with Physical Force,

or, more literally expressed, is identical with physical force, and, the matter of our bodies being the same, and the forces which operate upon it being the same, as in the inorganic world, the exhibition of life is no more due to an innate principle, a separate essence, a quid intus, a something within, than is the registry of time in a clock.

THE ORIGIN AND EVOLUTION OF LIFE.

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LECTURE III.

THE ORIGIN AND EVOLUTION OF LIFE.

CONTENTS.

Definitions of Physiology-Ancient Definitions of Life-Modern Defi nitions of Life-Difference between Organic and Inorganic Matter -The Property of Assimilation-Period of Development of LifeThe Theory of Evolution-Palæontology-The Cataclysms of Cuvier -The Operation of Existing Causes-The Age of the Earth-The Evolution of Fossil Forms.

Physiology (ovos, hoyoç), in our day, has a meaning very different from the old conception of the term. It is no longer a "description of nature" in general, according to its literal origin and primitive significance. The vast collection of facts in natural science, accumulated since physiology first was taught, has been classified in appropriate lists, and relegated to special and separate departments. The range of physiology in ancient times becomes apparent from the titles of the works of the oldest authors. Thus, Aristotle wrote a work entitled Historia, Partes, Incessus, Motus, Generatioque Animalium; atque Plantarum naturæ brevis descriptio. Aristotle was the first to use the term ói quσioλoyoi, designating as such, Thales, Anaximenes, Heraclitus, Diogenes, Empedocles and Anaxagoras, philosophers who were engaged in the study of the nature of things, their causes and commencements. Fernel first (1538) limited the term to the nature of man in health. Boerhaave and Haller used it in the sense of the use or actions of the various parts of the body. Synonims of Physiology were the Philosophy of Living Bodies, Dynamology, Organonomia, Zoonomia, Biology. Johannes Müller (1833), "who dealt the death blow to vitalism" in physiology, called it "The Physics of

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ANCIENT DEFINITIONS OF LIFE.

Organisms," basing it solely upon Anatomy, Chemistry and Physics.

Physiology, in its modern sense, is limited to the phenomena observed only in living things, and though really only more closely allied with subjects not especially endowed with life, it has gradually become disencumbered from necessary consideration of them. Physiology is, in short, biology, the science of life.

What, then, is Life?

A satisfactory definition of life in a few words was a want experienced long before physiology was studied as a separate branch of knowledge. With the ancients this question was easily answered. Life to them was a miracle, a supernatural creation. "Humanity in its infancy, like the infant still in humanity, was satisfied with a word it could not comprehend." Every inexplicable event, from an eclipse to an epidemic disease, was accepted as a miracle, and further inquiry was prevented, if not punished, indeed, as a presumption upon the prerogatives of the gods.

Ancient Definitions of Life.

Or, later, definitions of life were evolved from the revelries of metaphysics. Life, said Thales, of Miletus, emanates from water with every other earthly thing. According to Pythagoras, the principle of life is heat. Alcmeon thought that the principle of life was in the blood, but the soul, a distinct principle, was seated in the brain. The chief ingredient in the manufacture of life for Empedocles was fire, though water, air and earth, all the elements, entered into its composition. It was with fire stolen from heaven that Pygmalion infused the breath of life into his marble statue. Hippocrates, most wise of all, refrained from any definition of life, and counseled the study, not of its causes, but of its

ANCIENT DEFINITIONS OF LIFE.

49

manifestations. Plato, the great spiritualist, maintained that the rational soul, an immaterial essence, was located in the brain, the irrational, likewise an essence, in the abdomen. The body is only the theater in which the soul lives, and thinks and acts. Aristotle subdivided the soul to such extent as to localise its parts in every organ, whose functions the special parts direct. The still popular "animation" of the heart, stomach, bowels, liver, spleen and kidneys is the relic of these views. In the reaction which naturally followed this exaltation of the soul, Epicurus, like Democritus before him, renounced the soul entirely with every form of immateriality. The body is only an accidental collocation of atoms, whose aggregation and arrangement explains the different functions. Galen with his pneuma again restored the soul as the principle of life. It was developed in the ventricles of the brain, and lodged in the arteries, the air or pneuma carriers, whence they have their name. But with Galen came again the reinstatement of observation, as recommended by Hippocrates, and the first establishment of experiment. Galen is thus justly looked upon as the father and the founder of scientific physiology. Unfortunately, his example had no followers. "Fireside and writing-desk theories"-easier paths to notoriety-soon supplanted bed-side observations and experimental studies, one after another triumphing in turn, until everything was lost in the succeeding darkness of the middle ages. "The field of physiology illuminated for a moment by the genius of Galen was then enshrouded in twelve centuries of gloom."

After the long night of ignorance and superstition broke the dawn of the day which is still upon us in glimmers of light from the natural sciences. From the still smouldering embers of alchemy and astrology-as Christianity upon the altars of the unknown gods—were fanned the flames of modern chemistry, physics, and the other natural sciences, under