LITERARY COLUMN.

Press, Volume LIX, Issue 11491, 26 January 1903, Page 7

LITERARY COLUMN.

THE ORIGIN OF LIFE.

(By Professor W. B. Bexhav, D. Sα, Otago University.) Biologists are agreed that tie rttj varied form presented by living things, whether plants or animals, has been brought about by some kind of organic evolution: and by evolution is merely meant the gradual development of a more complex foam from a less complex ; the -derivation of U>* heterogeneous condition from the homogeneous. We need not concern ourselves here with the (juestion whether Darwin's theory ol •' Natural Selection," or the Lamajvkaan hypoUiesus, or any other of the suggested factors in Hie process be the more probable, but we aie all agreed that evolution has occurred in the organic world, juet as iv the inorganic world.

The astronomer attributee the origin or our solar system to some form of eoemical evolution. The geologist believes that the e;:rth itself, as we know it to-day, i* the result of a gradual evolution from a simpler condition, and it seems probable that organic, evolution has gone on step by etep with the geological evolution, and that at some point in time organic evolution linked in with the vusmical evolution.

At any rate, organic evolution is a fact. We maj trace the lineage of existing forma of animals in tlie fossilised remains in the sedimentary rocks of the earth's cruet. These carry us back to less and less complex forms, and as we pass further backward through geological ages, >w* mesi with successively simpler and stiL simpler animals. And so it is in the caee of plants. We liave every reason to be-iieve that all existing animals are descended (or ascended, if one wishes it) from one kind of extremely simple animal, which lived at a veiy early epoch of tho world's history: all existing plants from extremely simple plants.

Moreover, there is not lacking ground far the belief that these arthu.ic unknot and plants were preceded, in tin*?, by organisms which presented the special characters neither of animals nor of plants, organisme in which the peculiarities of tli'.se two sub-kingdoms of orga.nic nature had not yet become differentiated; for sttsh organisms, in fact, exist at tit? present day. so as to render impossible a htird and fa«t demarcation between these two sub-king-doms.

It k truo, of course, that we do aot find even in the easiest known sedimentary rocks, definite fossilised remains of U-Cfle earliest and sinvpkst organisms. Nor doee the biologist or tlie geologist expect to'find such remains, since the absence of hard parts, as well as the great simplicity of structure, and the probably smell site which w-d attribute to these early animals end plants, must have rendered them wtalit unable to withstand the various and repeated buffetings, chemical ati well a* xaechajiical, which the earliest deposits, fanning ths lower strata of the earth's cru«t, here had to undergo during the immerafe period of time that has intervened ginc» thess organisms lived and died on the just hardening surface of the cooling earth. Yet in spite of the total nb—nrw of any remains in the rocks, w* m*y b* quite certain that such simple aaowtnl organisms did exist—tube progenito» of the whole organic world of to-dayw- . '

The evolutionist, naturally, prate Uμ (jiiestioa to himself: How did thia first; «»• ganiam oiiyiuate? , ,

Jn ;iHe]isi:t»ig to answer thin questio*, we kvi.":! cur.sider the very simpket liriag iiuny-5 ti1, , .-: exist at the present time,' And attempt to discover in what manner aoi ia what de-i:e, living things differ tram USA* living things. To present this maitar ia its entire!/,- would occupy too nrocb wpto» iv the present -article. There ia tbt htm need for entering into details here, m tit* question is fully discussed in the ordinary text books on biology, and, notably, in Professor Huxley's article, "Bioiogy," ia the " Encyclopaedia Britannica. , ' Wβ may, therefore, at once state the conclusions to which- modem research by biologfets and chemists have led us, namely, that tbft essential and practically the only constant diSeienca between the organic and the inorganic world, lien in the chemical conatitoMoa of living substance, with which conabttation is associated ttae various peculiar power* or properties —such as metabolism, mciion, irritability, reproduction—that are M« soeiated' with the idea of life.

It may seem to the layman tliat otfcw ciilFcrtncss exist, but he must bear in mind that, in order to get to the root of toe matter, the comparison tfoafc has to be made does not lie beibween the highly complex man or even horse, but lies between the simple amoeba, and even still simpler organisms, on the one hand, and on the other band inorganic natter such as rocks, ma&er**, and chemical substances. Our definition of life, if we" were to formulate one, must be such as to embrace all kinds of animals and plants—complex, simple and microscopic— and their phenomena, and «t the auneutime exclude from its scope ail inorganic things and phenomena. .

The amoeba is familiar, by same at least, to all who have read any current literature dealing with the philosophy of biology. It consists of a small mass of a peculiar substar, oa known as protoplasm. It is able to carry on a! the usual function* of an animal—it moves about, it captures and digests, and may even select, food; it excretes waste matter; it grows in size; it is affected by changes in its surroundings (though, it is probably rot endowed with sentience); and finally it reproduce* its like.

This protopkem u> the basis of which aXL living things consist, be they animate or plants, be they large or smeil, nms>l« or complex.

Of what ihen does this reraaduble *nbstance consist? Do we find in it any chemical element peculiar to tai* living rabstance, and limited to it alone? Theaunrw is in the negative. On the contrary, tine protoplasm contains only *uoh ijiiilial «!*• nients as are among the very roimnoimt and most widely distributed.

When thie protoplasm invariably yield* us the five elements carbon, nitrogen, oxygen, hydrogen, and sulphur, aomefciinca a sixth, phosphorus, is present, with tzace* of some half a dozen other otrmnnfa, all of which occur in the air, water, andMMl uooed Uβ.

Bat in this living matter ti*eae five or mx chetndcal elemeate are combined in Bucn • way ac to form a number of cxtnemdy oompL«x compounds termed protetd** of vftidh the white of egg, or albumen, ia t&tm baatl known example.

And the important faot ia that these y*»teida are totaHy unknown outeidethe mytu world; they do not occur in Nature exeapb as a result of tibe vital adtivitiee of firiqg matter.

Further, tint living matter ia ebte to manufacture proteid*—able to oimifalxi tiiate chemical element* in iuch a way aa to form new proteids, and at t&e umt time proteid* thus formed are coatiaaaUy baing destrcyc-d by it—i.e., broken up into thii simple compounds, carbonic acid, anP* munia, and water, and discLarged from tie n>. ffa .m«m ..Xij - double OTOOUt Of M>

•!m'lation and dissimilation constitutes the peculiar series of chemical processes known to biologists as metabolism, itself a characteristic feature of living substance. It k impossible to write an empiric formula for proteids except in one or two casts; vet these cases, such ac eggs —albumen, and hcemoglobin, show us that uhe molecule of a proteid is of enormous size, as compared with any inorganic mibetanoe, and is composed of a vast number of atoms.

Id endeavouring to ascertain the chemical character of protoplasm, it is, of course, iiectssary to kill it, and dead protoplasm presents, us we may -well imagine, differences from living protoplasm, a* the proteids in the latteir condition no doubt undergo sundry chemical changes at death; conseq-uently the term "Biogen" has been applied to a molecule of living proteid. It is *he biogens alone that exhibit metabolism and the other phenomena peculiar to life. These proteide are not only always associated with life, or with the results of the vital activities at Irving eubstanoes, but life is unknown except in association with proteid. Aod, consequently, just ajj ye refer to the seniea of character*, fluidity, colourlessness, tr&nsparency, taateless-ness, and so forth, presented by the c&emicai substance water, as its "propemee," so we may say that the serivs <« phriK>m*nti cotiiiuted by the word "life" constitute the peculiar characteristic or property of those chemical substances termed proteids. Life, then, being the peculiar characteristic of proteids, the question ac to the origin of life resolves iteeif into the origin of the first mass of protoplasm, and thus the question becomes limited to "a discussion a.s to the mode ot origin of the first prateid substance on the surface of this earth.

Thy answer to the question : —What was the origin of life on the surface of this

Kirth? lies amongst three alternatives

1. Life 'has been, and is, eternal; it h&e arrived on the earth from elsewhere in th« universe. This is the theory of "•Coemozoa."

2. The first, living thing arose on this earth as a result of some supernatural process. This is the theory of "'Creation."

3. Life originated from non-living substances, in conformity with the general course of gradual changes from simple to complex, which has resulted, as we hold, in tlif origin of the solar system, and, later on, in the origin of the organic world as <we know it at the present day. This is the theory of "Evolution." Let us consider tlhese three possibilities.

1. The tlheory of the Cosniozoa was put forward in 1866 by Richter. He starts with t'hs fact that meteorites containing carbon and carbcn compounds, coming from other parts of the solar system, alight from tkn* to time upon the earth. Such smsril solid parti-cleg are continually being 'broken off the heavenly bodies, and are presumably moving about everywhere throughout space. , Ricnter suggest* that microscopic lifegerms exist upon these meteorites, and if euch a meteorite or meteoric dust fall on any of the heavenly 'bodies whose state of development presents favourable conditions for life, these life-germs begin to develop eikl give rise to living things. Helmholtz and Lord Kelvin discussed a annular tlheory as a possible one, and regarded it as "not unscientific." It is, to

■ome extent, bound up witlh the evolution of the cosmos. But it shifts the problem r from ih» origin of life on earth to the i larger croc, the origin of life in the uniBichter ooawideis life to -be eternal "<Soa»eWjher« dn epace," he says, "there have •hroye been heavenly 'bodies upon, ■which, life exiete in the form of cells." But modern research tends to show that organisms differ essentially from inorganic bodies only in their chemical nature; they do not stand ia fundamental contrast to

them, as fifty years ago was supposed to •be the eaee. Hence any general conclusion em to the derivation of proteid is probably equally applicable to inorganic compounds «ueh as quartz, fekpar, and other atokierftle. Now, if it be contended that proteid onaterial -has never originated, but me always existed, it is only logioal to extend thus conclusion to minerals, and to argue thai quartz and felepar are eternal, and aa such foave reached the earth from other ip&rta of tlhe universe. This Would lead to the *bsurd conclusion ell the constituents of the earth, 'have wandered about in space id their fully - formed condition, and <bave each end all re*dhed the earth as sudh.

But geologists a-re convinced that, at least, moot of these mineral* have been formed in situ during the cooling of the earth. If minerals and proteids have existed! eternally there ins, of course, •been no evolution at ell, no conversion of the one into tlhe other. But one fundamental fact in .plaifb physiology contradicts thia assumption, ttwt life hoe never originated from non-living, inorganic snbetancea, namely, toe fact that, every green jpknt. ia engaged, at the present day, in building up its own living material "from eanple chemical compounds present in the air and the soil.

If-■Wβ contrast the small seed pwt into th« soil in the spring with the comparatively Jarge plant that has grown therefrom by the autumn, we recognise that an enormous quantity of living substance must have beep' manufactured out of the ■purely inorganic substances of the earth, air, and water; and when ttinter comes almost tJie whole of this organic substance returns onoe more to simplier inorganic compounds. It is here seen liow inseparably . related are organic and inorganic nature.

This theory of Cosmozoa is founded on facts, and to thi« extent is a scientific one. It is, of course, impossible to assert that life is not eternal in this sense, or that the theory i« wrong. All that we may cay is tihai. it is extremely improbable, end that other theories afford a more reasonable explanation of the matter under diecmsßJon.

2. As to the theory of creation, science is, and must be, silent, since she has to do -with natural processes, of which evidence in ti)© form of facts, experimental and otherwise, is available. Of any extranatural process—i.e., a process of which "Wβ bare no scientific knowledge—science takes no cognisance; such a process belongs to the realm, not of science, but of metaphysics. And, am Haeckel remarks, "a conception of an immaterial force, nirhkh at the first creates nutter, is on article-of faith, which lias nothing whatever to do with human science, for where Faith commences Science ends." We may, therefore, leave out of further consideration the hypothesis of creation.