I
Ever since Rene Descartes, in his Holland laboratory, dissected the heads of great numbers of animals in order to discover the processes of imagination and memory, men have been seeking a physical or materialistic answer to such questions as, What is life? What is it to be alive? How shall we distinguish the living from the not-living?
No one of to-day, in the light of the correlation of vital processes with the general law of the conservation of energy, believes that life in plants and animals is a separate ent.i.ty which may exist outside of and apart from matter. In a scientific sense, we only know life by its a.s.sociation with living matter, which in its simplest form is known as _protoplasm_. The latter has been termed the physical basis of life, and so far as we know every material living thing is composed wholly of protoplasm and of the structures which it has built up.
This grayish, viscid, slimy, semi-transparent, semi-fluid substance, similar to the white of an egg, is the most puzzling, the most wonderful material with which science has to deal. Chemically it is composed of various proteids, fats, carbohydrates, etc., and these in turn of but very few elements, all of which are common, and none of which are peculiar to protoplasm itself. And yet its essential properties, its mechanical as well as its chemical make-up, have baffled the resources of our wisest men with all their retorts and microscopes and other instruments of precision.
Protoplasm is essentially uniform and similar in appearance and properties wherever found, whether in the tissues of the human body, in a blade of gra.s.s, or in the green slime of a stagnant pool. And yet probably no two samples of protoplasm are ever exactly similar in all respects, though we may never be able to detect their precise differences. These differences are due to the fact that the stuff is _alive_, and within it are constantly going on those changes accompanying metabolism, or the building up and tearing down processes that always accompany life. All separate ma.s.ses of protoplasm, such as the one-celled amoeba or the individual cells of our own bodies, are constantly taking in food and as constantly throwing off wastes. Hence, in the very nature of things, it is impossible to find any ma.s.s of protoplasm absolutely pure. And a further and impa.s.sable barrier to chemical a.n.a.lysis, or indeed to any adequate scientific examination, lies in the fact that we can never deal with protoplasm exactly as it is, since no a.n.a.lysis can be performed upon it without destroying its life. And yet even dead protoplasm, and especially its most characteristic const.i.tuent, _proteid_, has been found the most difficult material in the world to a.n.a.lyze, and n.o.body as yet pretends to know its exact chemical make-up.
The constant effort of natural science to press back the boundaries of the unknown is very liable to obscure some of the things most essential to any system of clear thinking regarding these matters. We are so p.r.o.ne to think that if only our microscopes were a little stronger, if only we could devise more effective methods of staining or of chemical a.n.a.lysis or chemical synthesis, we might really find out what life is, or what matter itself is; in short, that we might be able to solve in a scientific way the old, old riddle of existence. But already we have about reached the limits of the powers of the microscope; and even if we could devise a way of seeing the ultimate structures of which protoplasm is composed, how would we be any better off? Would we not have to attribute to each const.i.tuent of this living substance the properties which we now attribute to the whole?--that is, the properties which we attribute to ma.s.ses of protoplasmic units, such as plants, or birds, or human beings?
We look at ourselves and we feel sure that we have a separate and real existence, that we are rationally conscious and are endowed with choice and free will. We can say almost as much for an intelligent bird or dog.
But we hesitate to say how many of these powers or characteristics of free and independent personality can be a.s.signed to the unicellular organisms, such as the amoeba or the corpuscles of our blood. These one-celled creatures are also alive, are just as truly alive as are those composed of many cells. Even the corpuscles of which our bodies are composed move, and eat, and grow, and seem really endowed with intelligence like the higher forms of life. Suppose we could go further than is now possible and could lay bare the ultimate make-up of the _chromatin_ of these one-celled creatures, would we even then be able to prove that life with all its properties is inherent in these material components of the cells? In other words, would we really solve anything after all? Or would we not rather be compelled to acknowledge that the simplest, the most truly rational view of the question is that in living matter we have merely a special manifestation of the presence and the direct action of the G.o.d of nature which we cannot so readily recognize in not-living matter? This, it seems to me, is all that we really know, and all that we are likely ever to know.
When we examine carefully the differences between the living and the not-living, we see that the chief difference between them is in _their origin_. The matter of growth is not a real distinction; for crystals grow on the outside, while inorganic liquids grow by intussusception, as when a soluble substance is added to them, in very much the same way as an animal grows by the ingestion of food. Even movement is hardly an absolute distinction between the living and the not-living; for no movement can be detected in quiescent seeds, which may lie dormant for thousands of years; and on the other hand inorganic foams when brought into contact with liquids of different composition display movements that very closely simulate those of the living matter. Lastly, irritability, though so notably characteristic of living matter, is scarcely peculiar to it, for many inorganic substances seem almost as definitely responsive to external stimulation. But in the matter of _their origin_ there is a real and a most fundamental difference. All living substance arises only from other substance already living. It cannot arise from the not-living; or at least it never has done so since the beginning of scientific observation, though on this point have been concentrated the learning and the laboratory technique of thousands of chemists and microscopists.
It may not be out of place to quote here from one of the cla.s.sics dealing with this subject,--words that are just as true to-day as when first written nearly half a century ago:
"Let us place vividly in our imagination the picture of the two great kingdoms of nature,--the inorganic and the organic,--as these now stand in the light of the Law of Biogenesis. What essentially is involved in saying that there is no spontaneous generation of life? It is meant that the pa.s.sage from the mineral world to the plant or animal world is hermetically sealed on the mineral side. This inorganic world is staked off from the living world by barriers that have never yet been crossed from within. No change of substance, no modification of environment, no chemistry, no electricity, nor any form of energy, nor any evolution, can endow a single atom of the mineral world with the attribute of life. Only by the bending down into this dead world of some living form can these dead atoms be gifted with the properties of vitality; without this preliminary contact with life they remain fixed in the inorganic sphere forever.
"It is a very mysterious law which guards in this way the portals of the living world. And if there is one thing in nature more worth pondering for its strangeness, it is the spectacle of this vast helpless world of the dead cut off from the living by the Law of Biogenesis, and denied forever the possibility of resurrection within itself. The physical laws may explain the inorganic world; the biological laws may account for the development of the organic. But of the point where they meet,--of that strange border-land between the dead and the living,--science is silent.
It is as if G.o.d had placed everything in earth and heaven in the hands of nature, but had reserved a point at the genesis of life for His direct appearing."[6]
[Footnote 6: Henry Drummond, "Natural Law in the Spiritual World,"
Chapter I.]
It would be superfluous to emphasize further this great outstanding fact that the not-living cannot become the living by any of the processes which we call natural; and it would be presumptuous to attempt to emulate these eloquent words by seeking to emphasize the completeness with which this great Law of Biogenesis confirms the truth of a real Creation; for the supreme grandeur and importance of this law could be only obscured by so doing.
II
Perhaps some of the most impressive lessons on this subject will be found in connection with the history of the discovery of this great Law of Biogenesis, which says that life can come only from life. For by studying the history of the way in which this great Law has been established, we cannot fail to be impressed with the thought that back of all the complex array of living forms in our modern world which go on perpetuating themselves in orderly ways according to natural law, they could have originated only by a direct and real Creation, essentially and radically different from any processes now going on.
The wisest of the ancients in Greece and Rome knew nothing of this great law as we now know it. Aristotle, the embodiment of all that the ancient world knew of natural science, expressly taught that the lower forms of animals, such as fleas and worms, even mice and frogs, sprang up spontaneously from the moist earth. "All dry bodies," he declared, "which become damp, and all damp bodies which are dried, engender animal life." According to Vergil, bees are produced from the putrifying entrails of a young bull. Such were the teachings of all the Greeks and Romans, even of the scientists of the post-Reformation period, some of whom had acc.u.mulated a very considerable stock of knowledge concerning plants and animals.
And similar absurdities continued to be taught until comparatively modern times. Van Helmont, a celebrated alchemist physician who flourished during the brilliant reign of Louis XIV, wrote: "The smells which arise from the bottom of mora.s.ses produce frogs, slugs, leeches, gra.s.ses, and other things." As a recipe for producing a pot of mice offhand, he says that the only thing necessary is partly to fill a vessel with corn and plug up the mouth of the vessel with an old dirty shirt. In about twenty-one days, the ferment arising from the dirty shirt reacting with the odor from the corn will effect the trans.m.u.tation of the wheat into mice. The doctor solemnly a.s.sures us that he himself had witnessed this wonderful fact, and continues, "The mice are born full-grown; there are both males and females. To reproduce the species it suffices to pair them."
"Scoop out a hole in a brick," he says further, "put into it some sweet basil, crushed, lay a second brick upon the first so that the hole may be completely covered. Expose the two bricks to the sun, and at the end of a few days the smell of the sweet basil, acting as a ferment, will change the herb into real scorpions."[7]
[Footnote 7: "Louis Pasteur, His Life and Labors," p. 89.]
Sir Thomas Browne, the famous author of "Religio Medici," had expressed a doubt as to whether mice may be bred by putrifaction; but another scientist, Alexander Ross, disposed of this suggestion by the following line of argument which was supposed to be conclusive as a _reductio ad absurdum_:
"So may he (Sir Thomas Browne) doubt whether in cheese and timber worms are generated; or if beetles and wasps in cows" dung; or if b.u.t.terflies, locusts, gra.s.shoppers, sh.e.l.l-fish, snails, eels, and such like, be procreated of putrid matter, which is apt to receive the form of that creature to which it is by formative power disposed. To question this is to question reason, sense and experience. If he doubts this let him go to Egypt, and there he will find the fields swarming with mice, begot of the mud of Nylus, to the great calamity of the in-habitants."[8]
[Footnote 8: Encyclopaedia Britannica, Vol. I, p. 64.]
When we remember that such nonsense const.i.tuted the wisdom of the scientific world only about two centuries ago, we begin to realize the fact that the doctrine of Biogenesis is indeed a very modern doctrine.
But it may be well to ask in pa.s.sing, How could the people of former ages understand or appreciate the great truth of Creation as we moderns are able to do?
The first important step toward the refutation of this old pagan doctrine of spontaneous generation was made by the Italian, Redi, in 1668. He noticed that flies are always present around decomposing meat before the appearance of maggots, and he devised an experiment to keep the flies away from actual contact with the meat. The meat putrified as usual, but did not breed maggots; while the same kind of meat exposed in open jars swarmed with them. He next placed some meat in a jar with some wire gauze over the top. The flies were attracted by the smell of the meat as usual, but could not reach the meat. Instead they laid their eggs upon the gauze, where they hatched in due time, while no maggots were generated in the meat. Thus from this time onward it became gradually understood that, at least in the case of all the larger and higher forms of life, Harvey"s dictum, as announced some years previously, was true, and that life comes only from life.
But the invention of the microscope opened the way for a renewal of the controversy regarding the origin of life. Bacteria were discovered in 1683; and it was soon observed that no precautions with screens or other stoppers could prevent bacteria and other low organisms from breeding in myriads in every kind of organic matter. Here apparently was an entirely new foundation for the doctrine of spontaneous generation. It was freely admitted that all the higher forms of life arise only by process of natural generation from others of their own kind; but did not these microscopic organisms prove that there was "a perpetual abiogenetic fount by which the first steps in the evolution of living organisms continued to arise, under suitable conditions, from inorganic matter"?[9]
[Footnote 9: Encyclopaedia Britannica, Vol. I, p. 64.]
The famous "barnacle-geese" ought not to be omitted from any sketch of the vicissitudes of this doctrine of Biogenesis. An elaborate ill.u.s.trated account covering their alleged natural history was printed in one of the early volumes of the Royal Society of London. Buds of a particular tree growing near the sea were described as producing barnacles, and these falling into the water were alleged to be trans.m.u.ted into geese. Nor should we omit mention of Huxley"s _Bathybius Haeckelii_, a slimy substance supposed to exist in great ma.s.ses in the depths of the ocean and to consist of undifferentiated protoplasm, the exhaustless fountain from which all other forms of life had been derived. Not long after Huxley had given it a formal scientific name in 1868, it was discovered to be merely a precipitate of gypsum thrown down from sea water by alcohol, and thus a product of clumsy manipulation in the laboratory, instead of a natural product of the deep sea. The disappointment of those opposing biogenesis was severe; but the lesson is still of value to the world to-day.
The masterly work of Tyndall and Louis Pasteur in doing for the bacteria and protozoa what Redi had done for the larger organisms, is too much a matter of modern contemporary history to need recital here. Upon this great truth of life only from life is based all the recent advances in the treatment and prevention of germ diseases and all the triumphs of modern surgery. The housewife puts up canned fruit with the utmost confidence because she believes in this great Law of Biogenesis. It is because we all believe in it that we use antiseptics and fumigators and fly screens.
III
But what are the lessons to be learned from this great fact, and what bearing has this fact on the old Bible doctrine of a literal Creation?
Life comes now only from preexisting life. But at some time there was no life on the globe. It does not take any great exercise of "philosophic faith," as Huxley suggested, "to look beyond the abyss of geologically recorded time" and recognize that at this beginning of things there must have taken place a most wonderful event, essentially and radically different from anything now going on, namely, the beginning of organic life. But would not this be a real Creation in the old-fashioned sense of this term? We cannot avoid this conclusion; nor is there anything in either science or philosophy to indicate that this creation of the living from the not-living was confined to _one mere speck_ of protoplasm. It is absolutely certain that it required a real Creation to produce life from the not-living at all; and it is just as reasonable that this exercise of creative power may have taken place _in all parts of the earth at the same general time_, as the Bible teaches. For if a Being saw fit to create life at all, why should He stop with one or two bits of protoplasmic units? An architect who can make his own bricks and other building material, can surely build what he desires out of these materials. Common sense tells us that, if the Creator really created life in the beginning, He did not stop with a few specks of protoplasm here and there over the earth. The ability to create life from the not-living implies the ability to make full-grown trees or birds or beasts in twenty-four hours, instead of waiting for months or years, as is usual at the present time.
As we have already found regarding matter and energy, so of life. The record in Genesis is confirmed, for modern science compels us to believe in Creation as the only possible origin of life,--a Creation entirely different from anything now going on, and one that can never be made to fit into any scheme of uniformitarian evolution.
IV
THE CELL AND THE LESSONS IT TEACHES
I
With his usual vigor and expressiveness Henry Drummond has given us a picture of the remarkable fact that the cells of all plants and animals are strikingly alike, especially the single cells from which all originate. It is easy for any one to distinguish between an oak, a palm tree, and a lichen, while a botanist will have elaborate scientific distinctions which he can discern between them. "But if the first young germs of these three plants are placed before him," says Drummond, and the botanist is called upon to define the difference, "he finds it impossible. He cannot even say which is which. Examined under the highest powers of the microscope, they yield no clue. a.n.a.lyzed by the chemist, with all the appliances of his laboratory, they keep their secret.
"The same experiment can be tried with the embryos of animals. Take the ovule of the worm, the eagle, the elephant, and of man himself. Let the most skilled observer apply the most searching tests to distinguish the one from the other, and he will fail.
"But there is something more surprising still. Compare next the two sets of germs, the vegetable and the animal, and there is no shade of difference. Oak and palm, worm and man, all start in life together. No matter into what strangely different forms they may afterwards develop, no matter whether they are to live on sea or land, creep or fly, swim or walk, think or vegetate,--in the embryo, as it first meets the eye of science, they are indistinguishable. The apple which fell in Newton"s garden, Newton"s dog Diamond, and Newton himself, began life at the same point."[10]
In these remarks, of course, Drummond is dealing with the unicellular primal form, "as it first meets the eye of science"; and while certain slight peculiarities (such as the constant number of chromosomes) have been detected as characteristic of the cells of certain forms, yet for all practical purposes these words of Drummond are just as true to-day as when first written. Possibly it is because of a failure in our technique or from a lack of power in our microscopes that these wonderful protoplasmic units from which all living things originate seem identical. But it is equally possible that they _are really identical_ in structure and in chemical composition, and that only the ever present watchcare of the great Author of nature directs the one to develop in a certain manner, "after its kind," and another in still another manner, "after its kind." At any rate, the _protoplasm_ of which they are all alike composed _is_ identical wherever found, so far as any scientific tests have yet been able to determine.
[Footnote 10: "Natural Law," Chapter X.]
II
There are many varieties of single cells known to science which maintain an independent individual existence. Among the unicellular plants are the bacteria, while the unicellular animals are known as the protozoa.
And although perhaps I ought to apologize to the reader for seeming to antic.i.p.ate here a part of the discussion of the problem of "species,"
yet it seems necessary to say a few words here regarding the "persistence" of these unicellular forms.
Among the diseases which have been proved to be due to protozoa are malaria, amoebic dysentery, and syphilis; while among the much larger number which are due to bacteria, bacilli, or other vegetable parasites, are cholera, typhoid fever, the plague, pneumonia, diphtheria, tuberculosis, and leprosy.