And herein is one of the mysteries of chemistry again. This support which the oxygen gives is utterly unlike any support we are acquainted with in the world of mechanical forces. Oxygen supports combustion by combining chemically with carbon, and the evolution of heat and light is the result. And this is another mystery--this chemical union which takes place in the ultimate particles of matter and which is so radically different from a mechanical mixture. In a chemical union the atoms are not simply in juxtaposition; they are, so to speak, inside of one another--each has swallowed another and lost its ident.i.ty, an impossible feat, surely, viewed in the light of our experiences with tangible bodies. In the visible, mechanical world no two bodies can occupy the same place at the same time, but apparently in chemistry they can and do. An atom of oxygen and one of carbon, or of hydrogen, unite and are lost in each other; it is a marriage wherein the two or three become one. In dealing with the molecules and atoms of matter we are in a world wherein the laws of solid bodies do not apply; friction is abolished, elasticity is perfect, and place and form play no part. We have escaped from matter as we know it, the solid, fluid, or gaseous forms, and are dealing with it in its fourth or ethereal estate. In breathing, the oxygen goes into the blood, not to stay there, but to unite with and bring away the waste of the system in the shape of carbon, and re-enter the air again as one of the elements of carbonic-acid gas, CO_{2}. Then the reverse process takes place in the vegetable world, the leaves breathe this poisonous gas, release the oxygen under the chemistry of the sun"s rays, and appropriate and store up the carbon. Thus do the animal and vegetable worlds play into each other"s hands. The animal is dependent upon the vegetable for its carbon, which it releases again, through the life processes, as carbonic-acid gas, to be again drawn into the cycle of vegetable life.
The act of breathing well ill.u.s.trates our mysterious relations to Nature--the cunning way in which she plays the princ.i.p.al part in our lives without our knowledge. How certain we are that we draw the air into our lungs--that we seize hold of it in some way as if it were a continuous substance, and pull it into our bodies! Are we not also certain that the pump sucks the water up through the pipe, and that we suck our iced drinks through a straw? We are quite unconscious of the fact that the weight of the superinc.u.mbent air does it all, that breathing is only to a very limited extent a voluntary act. It is controlled by muscular machinery, but that machinery would not act in a vacuum. We contract the diaphragm, or the diaphragm contracts under stimuli received through the medulla oblongata from those parts of the body which constantly demand oxygen, and a vacuum tends to form in the chest, which is constantly prevented by the air rushing in to fill it.
The expansive force of the air under its own weight causes the lungs to fill, just as it causes the bellows of the blacksmith to fill when he works the lever, and the water to rise in the pump when we force out the air by working the handle. Another unconscious muscular effort under the influence of nerve stimulus, and the air is forced out of the lungs, charged with the bodily waste which it is the function to relieve. But the wonder of it all is how slight a part our wills play in the process, and how our lives are kept going by a mechanical force from without, seconded or supplemented by chemical and vital forces from within.
The one chemical process with which we are familiar all our lives, but which we never think of as such, is fire. Here on our own hearthstones goes on this wonderful spectacular and beneficent transformation of matter and energy, and yet we are grown so familiar with it that it moves us not. We can describe combustion in terms of chemistry, just as we can describe the life-processes in similar terms, yet the mystery is no more cleared up in the one case than in the other. Indeed, it seems to me that next to the mystery of life is the mystery of fire. The oxidizing processes are identical, only one is a building up or integrating process, and the other is a pulling down or disintegrating process. More than that, we can evoke fire any time, by both mechanical and chemical means, from the combustible matter about us; but we cannot evoke life. The equivalents of life do not slumber in our tools as do the equivalents of fire. Hence life is the deeper mystery. The ancients thought of a spirit of fire as they did of a spirit of health and of disease, and of good and bad spirits all about them, and as we think of a spirit of life, or of a creative life principle. Are we as wide of the mark as they were? So think many earnest students of living things.
When we do not have to pa.s.s the torch of life along, but can kindle it in our laboratories, then this charge will a.s.sume a different aspect.
III
Nature works with such simple means! A little more or a little less of this or that, and behold the difference! A little more or a little less heat, and the face of the world is changed.
"And the little more, and how much it is, And the little less, and what worlds away!"
At one temperature water is solid, at another it is fluid, at another it is a visible vapor, at a still higher it is an invisible vapor that burns like a flame. All possible shades of color lurk in a colorless ray of light. A little more or a little less heat makes all the difference between a nebula and a sun, and between a sun and a planet. At one degree of heat the elements are dissociated; at a lower degree they are united. At one point in the scale of temperatures life appears; at another it disappears. With heat enough the earth would melt like a s...o...b..ll in a furnace, with still more it would become a vapor and float away like a cloud. More or less heat only makes the difference between the fluidity of water and the solidity of the rocks that it beats against, or of the banks that hold it.
The physical history of the universe is written in terms of heat and motion. Astronomy is the story of cooling suns and worlds. At a low enough temperature all chemical activity ceases. In our own experience we find that frost will blister like flame. In the one case heat pa.s.ses into the tissues so quickly and in such quant.i.ty that a blister ensues; in the other, heat is abstracted so quickly and in such quant.i.ty that a like effect is produced. In one sense, life is a thermal phenomenon; so are all conditions of fluids and solids thermal phenomena.
Great wonders Nature seems to achieve by varying the arrangement of the same particles. Arrange or unite the atoms of carbon in one way and you have charcoal; a.s.semble the same atoms in another order, and you have the diamond. The difference between the pearl and the oyster-sh.e.l.l that holds it is one of structure or arrangement of the same particles of matter. Arrange the atoms of silica in one way and you have a quartz pebble, in another way and you have a precious stone. The chemical const.i.tuents of alcohol and ether are the same; the difference in their qualities and properties arises from the way the elements are compounded--the way they take hold of hands, so to speak, in that marriage ceremony which const.i.tutes a chemical compound. Compounds identical in composition and in molecular formulae may yet differ widely in physical properties; the elements are probably grouped in different ways, the atoms of carbon or of hydrogen probably carry different amounts of potential energy, so that the order in which they stand related to one another accounts for the different properties of the same chemical compounds. Different groupings of the same atoms of any of the elements result in a like difference of physical properties.
The physicists tell us that what we call the qualities of things, and their structure and composition, are but the expressions of internal atomic movements. A complex substance simply means a whirl, an intricate dance, of which chemical composition, histological structure, and gross configuration are the figures. How the atoms take hold of hands, as it were, the way they face, the poses they a.s.sume, the speed of their gyrations, the partners they exchange, determine the kinds of phenomena we are dealing with.
There is a striking a.n.a.logy between the letters of our alphabet and their relation to the language of the vast volume of printed books, and the eighty or more primary elements and their relation to the vast universe of material things. The a.n.a.logy may not be in all respects a strictly true one, but it is an illuminating one. Our twenty-six letters combined and repeated in different orders give us the many thousand words our language possesses, and these words combined and repeated in different orders give us the vast body of printed books in our libraries. The ultimate parts--the atoms and molecules of all literature, so to speak--are the letters of the alphabet. How often by changing a letter in a word, by reversing their order, or by subst.i.tuting one letter for another, we get a word of an entirely different meaning, as in umpire and empire, petrifaction and putrefaction, malt and salt, tool and fool. And by changing the order of the words in a sentence we express all the infinite variety of ideas and meanings that the books of the world hold.
The eighty or more primordial elements are Nature"s alphabet with which she writes her "infinite book of secrecy." Science shows pretty conclusively that the character of the different substances, their diverse qualities and properties, depend upon the order in which the atoms and molecules are combined. Change the order in which the molecules of the carbon and oxygen are combined in alcohol, and we get ether--the chemical formula remaining the same. Or take ordinary spirits of wine and add four more atoms of carbon to the carbon molecules, and we have the poison, carbolic acid. Pure alcohol is turned into a deadly poison by taking from it one atom of carbon and two of hydrogen. With the atoms of carbon, hydrogen, and oxygen, by combining them in different proportions and in different orders, Nature produces such diverse bodies as acetic acid, alcohol, sugar, starch, animal fats, vegetable oils, glycerine, and the like. So with the long list of hydrocarbons--gaseous, liquid, and solid--called paraffins, that are obtained from petroleum and that are all composed of hydrogen and carbon, but with a different number of atoms of each, like a different number of a"s or b"s or c"s in a word.
What an enormous number of bodies Nature forms out of oxygen by uniting it chemically with other primary elements! Thus by uniting it with the element silica she forms half of the solid crust of the globe; by uniting it with hydrogen in the proportion of two to one she forms all the water of the globe. With one atom of nitrogen united chemically with three atoms of hydrogen she forms ammonia. With one atom of carbon united with four atoms of hydrogen she spells marsh gas; and so on.
Carbon occurs in inorganic nature in two crystalline forms,--the diamond and black lead, or graphite,--their physical differences evidently being the result of their different molecular structure. Graphite is a good conductor of heat and electricity, and the diamond is not. Carbon in the organic world, where it plays such an important part, is non-crystalline. Under the influence of life its molecules are differently put together, as in sugar, starch, wood, charcoal, etc.
There are also two forms of phosphorus, but not two kinds; the same atoms are probably united differently in each. The yellow waxy variety has such an affinity for oxygen that it will burn in water, and it is poisonous. Bring this variety to a high temperature away from the air, and its molecular structure seems to change, and we have the red variety, which is tasteless, odorless, and non-poisonous, and is not affected by contact with the air. Such is the mystery of chemical change.
IV
Science has developed methods and implements of incredible delicacy. Its "microbalance" can estimate "the difference of weight of the order of the millionth of a milligram." Light travels at the speed of 186,000 miles a second, yet science can follow it with its methods, and finds that it travels faster with the current of running water than against it. Science has perfected a thermal instrument by which it can detect the heat of a lighted candle six miles away, and the warmth of the human face several miles distant. It has devised a method by which it can count the particles in the alpha rays of radium that move at a velocity of twenty thousand kilometers a second, and a method by which, through the use of a screen of zinc-sulphide, it can see the flashes produced by the alpha atoms when they strike this screen. It weighs and counts and calculates the motions of particles of matter so infinitely small that only the imagination can grasp them. Its theories require it to treat the ultimate particles into which it resolves matter, and which are so small that they are no longer divisible, as if they were solid bodies with weight and form, with centre and circ.u.mference, colliding with one another like billiard-b.a.l.l.s, or like cosmic bodies in the depths of s.p.a.ce, striking one another squarely, and, for aught I know, each going through another, or else grazing one another and glancing off. To particles of matter so small that they can no longer be divided or made smaller, the impossible feat of each going through the centre of another, or of each enveloping the other, might be affirmed of them without adding to their unthinkableness. The theory is that if we divide a molecule of water the parts are no longer water, but atoms of hydrogen and oxygen--real bodies with weight and form, and storehouses of energy, but no longer divisible.
Indeed, the atomic theory of matter leads us into a non-material world, or a world the inverse of the solid, three-dimensioned world that our senses reveal to us, or to matter in a fourth estate. We know solids and fluids and gases; but emanations which are neither we know only as we know spirits and ghosts--by dreams or hearsay. Yet this fourth or ethereal estate of matter seems to be the final, real, and fundamental condition.
How it differs from spirit is not easy to define. The beta ray of radium will penetrate solid iron a foot thick, a feat that would give a spirit pause. The ether of s.p.a.ce, which science is coming more and more to look upon as the mother-stuff of all things, has many of the attributes of Deity. It is omnipresent and all-powerful. Neither time nor s.p.a.ce has dominion over it. It is the one immutable and immeasurable thing in the universe. From it all things arise and to it they return. It is everywhere and nowhere. It has none of the finite properties of matter--neither parts, form, nor dimension; neither density nor tenuity; it cannot be compressed nor expanded nor moved; it has no inertia nor ma.s.s, and offers no resistance; it is subject to no mechanical laws, and no instrument or experiment that science has yet devised can detect its presence; it has neither centre nor circ.u.mference, neither extension nor boundary. And yet science is as convinced of its existence as of the solid ground beneath our feet. It is the one final reality in the universe, if we may not say that it is the universe. Tremors or vibrations in it reach the eye and make an impression that we call light; electrical oscillations in it are the source of other phenomena.
It is the fountain-head of all potential energy. The ether is an invention of the scientific imagination. We had to have it to account for light, gravity, and the action of one body upon another at a distance, as well as to account for other phenomena. The ether is not a body, it is a medium. All bodies are in motion; matter moves; the ether is in a state of absolute rest. Says Sir Oliver Lodge, "The ether is strained, and has the property of exerting strain and recoil." An electron is like a knot in the ether. The ether is the fluid of fluids, yet its tension or strain is so great that it is immeasurably more dense than anything else--a phenomenon that may be paralleled by a jet of water at such speed that it cannot be cut with a sword or severed by a hammer. It is so subtle or imponderable that solid bodies are as vacuums to it, and so pervasive that all conceivable s.p.a.ce is filled with it; "so full," says Clerk Maxwell, "that no human power can remove it from the smallest portion of s.p.a.ce, or produce the slightest flaw in its infinite continuity."
The scientific imagination, in its attempts to master the workings of the material universe, has thus given us a creation which in many of its attributes rivals Omnipotence. It is the sum of all contradictions, and the source of all reality. The gross matter which we see and feel is one state of it; electricity, which is without form and void, is another state of it; and our minds and souls, Sir Oliver Lodge intimates, may be still another state of it. But all these theories of physical science are justified by their fruits. The atomic theory of matter, and the kinetic theory of gases, are mathematically demonstrated. However unreal and fantastic they may appear to our practical faculties, conversant only with ponderable bodies, they bear the test of the most rigid and exact experimentation.
V
After we have marveled over all these hidden things, and been impressed by the world within world of the material universe, do we get any nearer to the mystery of life? Can we see where the tremendous change from the non-living to the living takes place? Can we evoke life from the omnipotent ether, or see it arise in the whirling stream of atoms and electrons? Molecular science opens up to us a world where the infinitely little matches the infinitely great, where matter is dematerialized and answers to many of the conceptions of spirit; but does it bring us any nearer the origin of life? Is radio-active matter any nearer living matter than is the clod under foot? Are the darting electrons any more vital than the shooting-stars? Can a flash of radium emanations on a zinc-sulphide plate kindle the precious spark? It is probably just as possible to evoke vitality out of the clash of billiard-b.a.l.l.s as out of the clash of atoms and electrons. This allusion to billiard-b.a.l.l.s recalls to my mind a striking pa.s.sage from Tyndall"s famous Belfast Address which he puts in the mouth of Bishop Butler in his imaginary argument with Lucretius, and which shows how thoroughly Tyndall appreciated the difficulties of his own position in advocating the theory of the physico-chemical origin of life.
The atomic and electronic theory of matter admits one to a world that does indeed seem unreal and fantastic. "If my bark sinks," says the poet, ""t is to another sea." If the mind breaks through what we call gross matter, and explores its interior, it finds itself indeed in a vast under or hidden world--a world almost as much a creation of the imagination as that visited by Alice in Wonderland, except that the existence of this world is capable of demonstration. It is a world of the infinitely little which science interprets in terms of the infinitely large. Sir Oliver Lodge sees the molecular s.p.a.ces that separate the particles of any material body relatively like the interstellar s.p.a.ces that separate the heavenly bodies. Just as all the so-called solid matter revealed by our astronomy is almost infinitesimal compared with the s.p.a.ce through which it is distributed, so the electrons which compose the matter with which we deal are comparable to the bodies of the solar system moving in vast s.p.a.ces. It is indeed a fantastic world where science conceives of bodies a thousand times smaller than the hydrogen atom--the smallest body known to science; where it conceives of vibrations in the ether millions of millions times a second; where we are bombarded by a shower of corpuscles from a burning candle, or a gas-jet, or a red-hot iron surface, moving at the speed of one hundred thousand miles a second! But this almost omnipotent ether has, after all, some of the limitations of the finite. It takes time to transmit the waves of light from the sun and the stars. This measurable speed, says Sir Oliver Lodge, gives the ether away, and shows its finite character.
It seems as if the theory of the ether must be true, because it fits in so well with the enigmatic, contradictory, incomprehensible character of the universe as revealed to our minds. We can affirm and deny almost anything of the ether--that it is immaterial, and yet the source of all material; that it is absolutely motionless, yet the cause of all motion; that it is the densest body in nature, and yet the most rarified; that it is everywhere, but defies detection; that it is as undiscoverable as the Infinite itself; that our physics cannot prove it, though they cannot get along without it. The ether inside a ma.s.s of iron or of lead is just as dense as the ether outside of it--which means that it is not dense at all, in our ordinary use of the term.
VI
There are physical changes in matter, there are chemical changes, and there is a third change, as unlike either of these as they are unlike each other. I refer to atomic change, as in radio-activity, which gives us lead from helium--a spontaneous change of the atoms. The energy that keeps the earth going, says Soddy, is to be sought for in the individual atoms; not in the great heaven-shaking voice of thunder, but in the still small voice of the atoms. Radio-activity is the mainspring of the universe. The only elements so far known that undergo spontaneous change are uranium and thorium. One pound of uranium contains and slowly gives out the same amount of energy that a hundred tons of coal evolves in its combustion, but only one ten-billionth part of this amount is given out every year.
Man, of course, reaps where he has not sown. How could it be otherwise?
It takes energy to sow or plant energy. We are exhausting the coal, the natural gas, the petroleum of the rocks, the fertility of the soil. But we cannot exhaust the energy of the winds or the tides, or of falling water, because this energy is ever renewed by gravity and the sun. There can be no exhaustion of our natural mechanical and chemical resources, as some seem to fear.
I recently visited a noted waterfall in the South where electric power is being developed on a large scale. A great column of water makes a vertical fall of six hundred feet through a steel tube, and in the fall develops two hundred and fifty thousand horse-power. The water comes out of the tunnel at the bottom, precisely the same water that went in at the top; no change whatever has occurred in it, yet a vast amount of power has been taken out of it, or, rather, generated by its fall.
Another drop of six hundred feet would develop as much more; in fact, the process may be repeated indefinitely, the same amount of power resulting each time, without effecting any change in the character of the water. The pull of gravity is the source of the power which is distributed hundreds of miles across the country as electricity. Two hundred and fifty thousand invisible, immaterial, noiseless horses are streaming along these wires with incredible speed to do the work of men and horses in widely separated parts of the country. A river of sand falling down those tubes, if its particles moved among themselves with the same freedom that those of the water do, would develop the same power. The attraction of gravitation is not supposed to be electricity, and yet here out of its pull upon the water comes this enormous voltage!
The fact that such a mysterious and ubiquitous power as electricity can be developed from the action of matter without any alteration in its particles, suggests the question whether or not this something that we call life, or life-force, may not slumber in matter in the same way; but the secret of its development we have not yet learned, as we have that of electricity.
Radio-activity is uninfluenced by external conditions; hence we are thus far unable to control it. Nothing that is known will effect the trans.m.u.tation of one element into another. It is spontaneous and uncontrollable. May not life be spontaneous in the same sense?
The release of the energy a.s.sociated with the structure of the atoms is not available by any of our mechanical appliances. The process of radio-activity involves the expulsion of atoms of helium with a velocity three hundred times greater than that ever previously known for any material ma.s.s or particle, and this power we are incompetent to use. The atoms remain unchanged amid the heat and pressure of the laboratory of nature. Iron and oxygen and so forth remain the same in the sun as here on the earth.
Science strips gross matter of its grossness. When it is done with it, it is no longer the obstructive something we know and handle; it is reduced to pure energy--the line between it and spirit does not exist.
We have found that bodies are opaque only to certain rays; the X-ray sees through this too too solid flesh. Bodies are ponderable only to our dull senses; to a finer hand than this the door or the wall might offer no obstruction; a finer eye than this might see the emanations from the living body; a finer ear might hear the clash of electrons in the air.
Who can doubt, in view of what we already know, that forces and influences from out the heavens above, and from the earth beneath, that are beyond our ken, play upon us constantly?
The final mystery of life is no doubt involved in conditions and forces that are quite outside of or beyond our conscious life activities, in forces that play about us and upon and through us, that we know not of, because a knowledge of them is not necessary to our well-being. "Our eye takes in only an octave of the vibrations we call light," because no more is necessary for our action or our dealing with things. The invisible rays of the spectrum are potent, but they are beyond the ken of our senses. There are sounds or sound vibrations that we do not hear; our sense of touch cannot recognize a gossamer, or the gentler air movements.
I began with the contemplation of the beauty and terror of the thunderbolt--"G.o.d"s autograph," as one of our poets (Joel Benton) said, "written upon the sky." Let me end with an allusion to another aspect of the storm that has no terror in it--the bow in the clouds: a sudden apparition, a cosmic phenomenon no less wonderful and startling than the lightning"s flash. The storm with terror and threatened destruction on one side of it, and peace and promise on the other! The bow appears like a miracle, but it is a commonplace of nature; unstable as life, and beautiful as youth. The raindrops are not changed, the light is not changed, the laws of the storms are not changed; and yet, behold this wonder!
But all these strange and beautiful phenomena springing up in a world of inert matter are but faint symbols of the mystery and the miracle of the change of matter from the non-living to the living, from the elements in the clod to the same elements in the brain and heart of man.
IV
THE BAFFLING PROBLEM
I
Still the problem of living things haunts my mind and, let me warn my reader, will continue to haunt it throughout the greater part of this volume. The final truth about it refuses to be spoken. Every effort to do so but gives one new evidence of how insoluble the problem is.
In this world of change is there any other change to be compared with that in matter, from the dead to the living?--a change so great that most minds feel compelled to go outside of matter and invoke some super-material force or agent to account for it. The least of living things is so wonderful, the phenomena it exhibits are so fundamentally unlike those of inert matter, that we invent a word for it, _vitality_; and having got the word, we conceive of a vital force or principle to explain vital phenomena. Hence vitalism--a philosophy of living things, more or less current in the world from Aristotle"s time down to our own.
It conceives of something in nature super-mechanical and super-chemical, though inseparably bound up with these things. There is no life without material and chemical forces, but material and chemical forces do not hold the secret of life. This is vitalism as opposed to mechanism, or scientific materialism, which is the doctrine of the all-sufficiency of the physical forces operating in the inorganic world to give rise to all the phenomena of the organic world--a doctrine coming more and more in vogue with the progress of physical science. Without holding to any belief in the supernatural or the teleological, and while adhering to the idea that there has been, and can be, no break in the causal sequence in this world, may one still hold to some form of vitalism, and see in life something more than applied physics and chemistry?
Is biology to be interpreted in the same physical and chemical terms as geology? Are biophysics and geophysics one and the same? One may freely admit that there cannot be two kinds of physics, nor two kinds of chemistry--not one kind for a rock, and another kind for a tree, or a man. There are not two species of oxygen, nor two of carbon, nor two of hydrogen and nitrogen--one for living and one for dead matter. The water in the human body is precisely the same as the water that flows by in the creek or that comes down when it rains; and the sulphur and the lime and the iron and the phosphorus and the magnesium are identical, so far as chemical a.n.a.lysis can reveal, in the organic and the inorganic worlds. But are we not compelled to think of a kind of difference between a living and a non-living body that we cannot fit into any of the mechanical or chemical concepts that we apply to the latter?
Professor Loeb, with his "Mechanistic Conception of Life"; Professor Henderson, of Harvard, with his "Fitness of the Environment"; Professor Le Dantec, of the Sorbonne in Paris, with his volume on "The Nature and Origin of Life," published a few years since; Professor Schafer, President of the British a.s.sociation, Professor Verworn of Bonn, and many others find in the laws and properties of matter itself a sufficient explanation of all the phenomena of life. They look upon the living body as only the sum of its physical and chemical activities; they do not seem to feel the need of accounting for life itself--for that something which confers vitality upon the heretofore non-vital elements. That there is new behavior, that there are new chemical compounds called organic,--tens of thousands of them not found in inorganic nature,--that there are new processes set up in aggregates of matter,--growth, a.s.similation, metabolism, reproduction, thought, emotion, science, civilization,--no one denies.
How are we going to get these things out of the old physics and chemistry without some new factor or agent or force? To help ourselves out here with a "vital principle," or with spirit, or a creative impulse, as Bergson does, seems to be the only course open to certain types of mind. Positive science cannot follow us in this step, because science is limited to the verifiable. The stream of forces with which it deals is continuous; it must find the physical equivalents of all the forces that go into the body in the output of the body, and it cannot admit of a life force which it cannot trace to the physical forces.
What has science done to clear up this mystery of vitality? Professor Loeb, our most eminent experimental biologist, has succeeded in fertilizing the eggs of some low forms of sea life by artificial means; and in one instance, at least, it is reported that the fatherless form grew to maturity. This is certainly an interesting fact, but takes us no nearer the solution of the mystery of vitality than the fact that certain chemical compounds may stimulate the organs of reproduction helps to clear up the mystery of generation; or the fact that certain other chemical compounds help the digestive and a.s.similative processes and further the metabolism of the body a.s.sists in clearing up the mystery that attaches to these things. In all such cases we have the living body to begin with. The egg of the sea-urchin and the egg of the jelly-fish are living beings that responded to certain chemical substances, so that a process is set going in their cell life that is equivalent to fertilization. It seems to me that the result of all Professor Loeb"s valuable inquiries is only to give us a more intimate sense of how closely mechanical and chemical principles are a.s.sociated and identified with all the phenomena of life and with all animal behavior. Given a living organism, mechanics and chemistry will then explain much of its behavior--practically all the behavior of the lower organisms, and much of that of the higher. Even when we reach man, our reactions to the environment and to circ.u.mstances play a great part in our lives; but dare we say that will, liberty of choice, ideation, do not play a part also? How much reality there is in the so-called animal will, is a problem; but that there is a foundation for our belief in the reality of the human will, I, for one, do not for a moment doubt. The discontinuity here is only apparent and not real. We meet with the same break when we try to get our mental states, our power of thought--a poem, a drama, a work of art, a great oration--out of the food we eat; but life does it, though our science is none the wiser for it. Our physical life forms a closed circle, science says, and what goes into our bodies as physical force, must come out in physical force, or as some of its equivalents. Well, one of the equivalents, transformed by some unknown chemism within us, is our psychic force, or states of consciousness. The two circles, the physical and the psychical, are not concentric, as Fiske fancied, but are linked in some mysterious way.