Method By Which the Causes of the Present and Past Conditions of Organic Nature Are to Be Discovered — the Origination of Living Beings
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Method By Which the Causes of the Present and Past Conditions of Organic Nature Are to Be Discovered — the Origination of Living Beings

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The Project Gutenberg EBook of The Method By Which The Causes Of The Present And Past Conditions Of Organic Nature Are To Be Discovered.--The Origination Of Living Beings, by Thomas H. Huxley This eBook is for the use of anyone anywhere at no cost and with almost no restrictions whatsoever. You may copy it, give it away or re-use it under the terms of the Project Gutenberg License included with this eBook or online at www.gutenberg.org Title: The Method By Which The Causes Of The Present And Past Conditions Of Organic Nature Are To Be Discovered.--The Origination Of Living Beings Lecture III. (of VI.), Lectures To Working Men, at the Museum of Practical Geology, 1863, On Darwin's work: "Origin of Species". Author: Thomas H. Huxley Release Date: January 4, 2009 [EBook #2923] Language: English Character set encoding: ASCII *** START OF THIS PROJECT GUTENBERG EBOOK CAUSES DISCOVERED *** Produced by Amy E. Zelmer, and David Widger THE METHOD BY WHICH THE CAUSES OF THE PRESENT AND PAST CONDITIONS OF ORGANIC NATURE ARE TO BE DISCOVERED. THE ORIGINATION OF LIVING BEINGS Lecture III. (of VI.), "Lectures To Working Men", at the Museum of Practical Geology, 1863, On Darwin's work: "Origin of Species". By Thomas H.

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The Project Gutenberg EBook of The Method By Which The Causes Of ThePresent And Past Conditions Of Organic Nature Are To Be Discovered.--The Origination Of Living Beings, by Thomas H. HuxleyThis eBook is for the use of anyone anywhere at no cost and withalmost no restrictions whatsoever. You may copy it, give it away orre-use it under the terms of the Project Gutenberg License includedwith this eBook or online at www.gutenberg.orgTitle: The Method By Which The Causes Of The Present And Past Conditions Of Organic Nature Are To Be Discovered.--The Origination Of Living Beings       Lecture III. (of VI.), Lectures To Working Men, at the              Museum of Practical Geology, 1863, On Darwin's work: "Origin              of Species".Author: Thomas H. HuxleyRelease Date: January 4, 2009 [EBook #2923]Language: EnglishCharacter set encoding: ASCII*** START OF THIS PROJECT GUTENBERG EBOOK CAUSES DISCOVERED ***Produced by Amy E. Zelmer, and David WidgerTHE METHOD BY WHICH THECAUSES OF THE PRESENT AND PASTCONDITIONS OF ORGANIC NATURE ARE TOBE DISCOVERED.THE ORIGINATION OF LIVINGBEINGSLecture III. (of VI.), "Lectures To Working Men", atthe Museum of Practical Geology, 1863, On Darwin'swork: "Origin of Species".By Thomas H. HuxleyIn the two preceding lectures I have endeavoured toindicate to you the extent of the subject-matter of theinquiry upon which we are engaged; and now, having thusacquired some conception of the Past and Presentphenomena of Organic Nature, I must now turn to thatwhich constitutes the great problem which we have setbefore ourselves;—I mean, the question of whatknowledge we have of the causes of these phenomena oforganic nature, and how such knowledge is obtainable.Here, on the threshold of the inquiry, an objection meetsus. There are in the world a number of extremely worthy,well-meaning persons, whose judgments and opinionsare entitled to the utmost respect on account of theirsincerity, who are of opinion that Vital Phenomena, andespecially all questions relating to the origin of vitalphenomena, are questions quite apart from the ordinaryrun of inquiry, and are, by their very nature, placed out ofour reach. They say that all these phenomena originatedmiraculously, or in some way totally different from theordinary course of nature, and that therefore they conceiveit to be futile, not to say presumptuous, to attempt toinquire into them.To such sincere and earnest persons, I would only say,that a question of this kind is not to be shelved upon
theoretical or speculative grounds. You may remember thestory of the Sophist who demonstrated to Diogenes in themost complete and satisfactory manner that he could notwalk; that, in fact, all motion was an impossibility; and thatDiogenes refuted him by simply getting up and walkinground his tub. So, in the same way, the man of sciencereplies to objections of this kind, by simply getting up andwalking onward, and showing what science has done andis doing—by pointing to that immense mass of facts whichhave been ascertained and systematized under the formsof the great doctrines of Morphology, of Development, ofDistribution, and the like. He sees an enormous mass offacts and laws relating to organic beings, which stand onthe same good sound foundation as every other naturallaw; and therefore, with this mass of facts and laws beforeus, therefore, seeing that, as far as organic matters havehitherto been accessible and studied, they have shownthemselves capable of yielding to scientific investigation,we may accept this as proof that order and law reign thereas well as in the rest of nature; and the man of sciencesays nothing to objectors of this sort, but supposes that wecan and shall walk to a knowledge of the origin of organicnature, in the same way that we have walked to aknowledge of the laws and principles of the inorganicworld.But there are objectors who say the same fromignorance and ill-will. To such I would reply that theobjection comes ill from them, and that the realpresumption, I may almost say the real blasphemy, in thismatter, is in the attempt to limit that inquiry into the causesof phenomena which is the source of all human blessings,and from which has sprung all human prosperity andprogress; for, after all, we can accomplish comparativelylittle; the limited range of our own faculties bounds us onevery side,—the field of our powers of observation is smallenough, and he who endeavours to narrow the sphere ofour inquiries is only pursuing a course that is likely toproduce the greatest harm to his fellow-men.But now, assuming, as we all do, I hope, that thesephenomena are properly accessible to inquiry, and settingout upon our search into the causes of the phenomena oforganic nature, or, at any rate, setting out to discover howmuch we at present know upon these abstruse matters,the question arises as to what is to be our course ofproceeding, and what method we must lay down for ourguidance. I reply to that question, that our method must beexactly the same as that which is pursued in any otherscientific inquiry, the method of scientific investigationbeing the same for all orders of facts and phenomenawhatsoever.I must dwell a little on this point, for I wish you to leavethis room with a very clear conviction that scientificinvestigation is not, as many people seem to suppose,some kind of modern black art. I say that you might easilygather this impression from the manner in which manypersons speak of scientific inquiry, or talk about inductiveand deductive philosophy, or the principles of the"Baconian philosophy." I do protest that, of the vastnumber of cants in this world, there are none, to my mind,so contemptible as the pseudoscientific cant which istalked about the "Baconian philosophy."To hear people talk about the great Chancellor—and avery great man he certainly was,—you would think that itwas he who had invented science, and that there was nosuch thing as sound reasoning before the time of QueenElizabeth. Of course you say, that cannot possibly be true;you perceive, on a moment's reflection, that such an ideais absurdly wrong, and yet, so firmly rooted is this sort ofimpression,—I cannot call it an idea, or conception,—thething is too absurd to be entertained,—but so completelydoes it exist at the bottom of most men's minds, that thishas been a matter of observation with me for many yearspast. There are many men who, though knowingabsolutely nothing of the subject with which they may bedealing, wish, nevertheless, to damage the author of someview with which they think fit to disagree. What they do,then, is not to go and learn something about the subject,which one would naturally think the best way of fairlydealing with it; but they abuse the originator of the viewthey question, in a general manner, and wind up by sayingthat, "After all, you know, the principles and method of thisauthor are totally opposed to the canons of the Baconianphilosophy." Then everybody applauds, as a matter ofcourse, and agrees that it must be so. But if you were tostop them all in the middle of their applause, you wouldprobably find that neither the speaker nor his applauderscould tell you how or in what way it was so; neither theone nor the other having the slightest idea of what theymean when they speak of the "Baconian philosophy."You will understand, I hope, that I have not the slightestdesire to join in the outcry against either the morals, the
intellect, or the great genius of Lord Chancellor Bacon. Hewas undoubtedly a very great man, let people say whatthey will of him; but notwithstanding all that he did forphilosophy, it would be entirely wrong to suppose that themethods of modern scientific inquiry originated with him,or with his age; they originated with the first man, whoeverhe was; and indeed existed long before him, for many ofthe essential processes of reasoning are exerted by thehigher order of brutes as completely and effectively as byourselves. We see in many of the brute creation theexercise of one, at least, of the same powers of reasoningas that which we ourselves employ.The method of scientific investigation is nothing but theexpression of the necessary mode of working of thehuman mind. It is simply the mode at which allphenomena are reasoned about, rendered precise andexact. There is no more difference, but there is just thesame kind of difference, between the mental operations ofa man of science and those of an ordinary person, asthere is between the operations and methods of a baker orof a butcher weighing out his goods in common scales,and the operations of a chemist in performing a difficultand complex analysis by means of his balance and finely-graduated weights. It is not that the action of the scales inthe one case, and the balance in the other, differ in theprinciples of their construction or manner of working; butthe beam of one is set on an infinitely finer axis than theother, and of course turns by the addition of a muchsmaller weight.You will understand this better, perhaps, if I give yousome familiar example. You have all heard it repeated, Idare say, that men of science work by means of Inductionand Deduction, and that by the help of these operations,they, in a sort of sense, wring from Nature certain otherthings, which are called Natural Laws, and Causes, andthat out of these, by some cunning skill of their own, theybuild up Hypotheses and Theories. And it is imagined bymany, that the operations of the common mind can be byno means compared with these processes, and that theyhave to be acquired by a sort of special apprenticeship tothe craft. To hear all these large words, you would thinkthat the mind of a man of science must be constituteddifferently from that of his fellow men; but if you will not befrightened by terms, you will discover that you are quitewrong, and that all these terrible apparatus are being usedby yourselves every day and every hour of your lives.There is a well-known incident in one of Moliere's plays,where the author makes the hero express unboundeddelight on being told that he had been talking prose duringthe whole of his life. In the same way, I trust, that you willtake comfort, and be delighted with yourselves, on thediscovery that you have been acting on the principles ofinductive and deductive philosophy during the sameperiod. Probably there is not one here who has not in thecourse of the day had occasion to set in motion a complextrain of reasoning, of the very same kind, though differingof course in degree, as that which a scientific man goesthrough in tracing the causes of natural phenomena.A very trivial circumstance will serve to exemplify this.Suppose you go into a fruiterer's shop, wanting an apple,—you take up one, and, on biting it, you find it is sour; youlook at it, and see that it is hard and green. You take upanother one, and that too is hard, green, and sour. Theshopman offers you a third; but, before biting it, youexamine it, and find that it is hard and green, and youimmediately say that you will not have it, as it must besour, like those that you have already tried.Nothing can be more simple than that, you think; but ifyou will take the trouble to analyze and trace out into itslogical elements what has been done by the mind, you willbe greatly surprised. In the first place, you have performedthe operation of Induction. You found that, in twoexperiences, hardness and greenness in apples gotogether with sourness. It was so in the first case, and itwas confirmed by the second. True, it is a very smallbasis, but still it is enough to make an induction from; yougeneralize the facts, and you expect to find sourness inapples where you get hardness and greenness. Youfound upon that a general law, that all hard and greenapples are sour; and that, so far as it goes, is a perfectinduction. Well, having got your natural law in this way,when you are offered another apple which you find is hardand green, you say, "All hard and green apples are sour;this apple is hard and green, therefore this apple is sour."That train of reasoning is what logicians call a syllogism,and has all its various parts and terms,—its major premiss,its minor premiss, and its conclusion. And, by the help offurther reasoning, which, if drawn out, would have to beexhibited in two or three other syllogisms, you arrive atyour final determination, "I will not have that apple." Sothat, you see, you have, in the first place, established a
law by Induction, and upon that you have founded aDeduction, and reasoned out the special conclusion of theparticular case. Well now, suppose, having got your law,that at some time afterwards, you are discussing thequalities of apples with a friend: you will say to him, "It is avery curious thing,—but I find that all hard and greenapples are sour!" Your friend says to you, "But how do youknow that?" You at once reply, "Oh, because I have tried itover and over again, and have always found them to beso." Well, if we were talking science instead of commonsense, we should call that an Experimental Verification.And, if still opposed, you go further, and say, "I have heardfrom the people in Somersetshire and Devonshire, wherea large number of apples are grown, that they haveobserved the same thing. It is also found to be the case inNormandy, and in North America. In short, I find it to be theuniversal experience of mankind wherever attention hasbeen directed to the subject." Whereupon, your friend,unless he is a very unreasonable man, agrees with you,and is convinced that you are quite right in the conclusionyou have drawn. He believes, although perhaps he doesnot know he believes it, that the more extensiveVerifications are,—that the more frequently experimentshave been made, and results of the same kind arrived at,—that the more varied the conditions under which thesame results have been attained, the more certain is theultimate conclusion, and he disputes the question nofurther. He sees that the experiment has been tried underall sorts of conditions, as to time, place, and people, withthe same result; and he says with you, therefore, that thelaw you have laid down must be a good one, and he mustbelieve it.In science we do the same thing;—the philosopherexercises precisely the same faculties, though in a muchmore delicate manner. In scientific inquiry it becomes amatter of duty to expose a supposed law to every possiblekind of verification, and to take care, moreover, that this isdone intentionally, and not left to a mere accident, as inthe case of the apples. And in science, as in common life,our confidence in a law is in exact proportion to theabsence of variation in the result of our experimentalverifications. For instance, if you let go your grasp of anarticle you may have in your hand, it will immediately fallto the ground. That is a very common verification of one ofthe best established laws of nature—that of gravitation.The method by which men of science establish theexistence of that law is exactly the same as that by whichwe have established the trivial proposition about thesourness of hard and green apples. But we believe it insuch an extensive, thorough, and unhesitating mannerbecause the universal experience of mankind verifies it,and we can verify it ourselves at any time; and that is thestrongest possible foundation on which any natural lawcan rest.So much by way of proof that the method of establishinglaws in science is exactly the same as that pursued incommon life. Let us now turn to another matter (thoughreally it is but another phase of the same question), andthat is, the method by which, from the relations of certainphenomena, we prove that some stand in the position ofcauses towards the others.I want to put the case clearly before you, and I willtherefore show you what I mean by another familiarexample. I will suppose that one of you, on coming downin the morning to the parlour of your house, finds that atea-pot and some spoons which had been left in the roomon the previous evening are gone,—the window is open,and you observe the mark of a dirty hand on the window-frame, and perhaps, in addition to that, you notice theimpress of a hob-nailed shoe on the gravel outside. Allthese phenomena have struck your attention instantly, andbefore two minutes have passed you say, "Oh, somebodyhas broken open the window, entered the room, and runoff with the spoons and the tea-pot!" That speech is out ofyour mouth in a moment. And you will probably add, "Iknow there has; I am quite sure of it!" You mean to sayexactly what you know; but in reality what you have saidhas been the expression of what is, in all essentialparticulars, an Hypothesis. You do not 'know' it at all; it isnothing but an hypothesis rapidly framed in your ownmind! And it is an hypothesis founded on a long train ofinductions and deductions.What are those inductions and deductions, and howhave you got at this hypothesis? You have observed, inthe first place, that the window is open; but by a train ofreasoning involving many Inductions and Deductions, youhave probably arrived long before at the General Law—and a very good one it is—that windows do not open ofthemselves; and you therefore conclude that somethinghas opened the window. A second general law that youhave arrived at in the same way is, that tea-pots andspoons do not go out of a window spontaneously, and you
spoons do not go out of a window spontaneously, and youare satisfied that, as they are not now where you left them,they have been removed. In the third place, you look at themarks on the window-sill, and the shoemarks outside, andyou say that in all previous experience the former kind ofmark has never been produced by anything else but thehand of a human being; and the same experience showsthat no other animal but man at present wears shoes withhob-nails on them such as would produce the marks in thegravel. I do not know, even if we could discover any ofthose "missing links" that are talked about, that they wouldhelp us to any other conclusion! At any rate the law whichstates our present experience is strong enough for mypresent purpose.—You next reach the conclusion, that asthese kinds of marks have not been left by any otheranimals than men, or are liable to be formed in any otherway than by a man's hand and shoe, the marks inquestion have been formed by a man in that way. Youhave, further, a general law, founded on observation andexperience, and that, too, is, I am sorry to say, a veryuniversal and unimpeachable one,—that some men arethieves; and you assume at once from all these premisses—and that is what constitutes your hypothesis—that theman who made the marks outside and on the window-sill,opened the window, got into the room, and stole your tea-pot and spoons. You have now arrived at a 'Vera Causa';—you have assumed a Cause which it is plain iscompetent to produce all the phenomena you haveobserved. You can explain all these phenomena only bythe hypothesis of a thief. But that is a hypotheticalconclusion, of the justice of which you have no absoluteproof at all; it is only rendered highly probable by a seriesof inductive and deductive reasonings.I suppose your first action, assuming that you are a manof ordinary common sense, and that you have establishedthis hypothesis to your own satisfaction, will very likely beto go off for the police, and set them on the track of theburglar, with the view to the recovery of your property. Butjust as you are starting with this object, some personcomes in, and on learning what you are about, says, "Mygood friend, you are going on a great deal too fast. Howdo you know that the man who really made the marks tookthe spoons? It might have been a monkey that took them,and the man may have merely looked in afterwards." Youwould probably reply, "Well, that is all very well, but yousee it is contrary to all experience of the way tea-pots andspoons are abstracted; so that, at any rate, yourhypothesis is less probable than mine." While you aretalking the thing over in this way, another friend arrives,one of that good kind of people that I was talking of a littlewhile ago. And he might say, "Oh, my dear sir, you arecertainly going on a great deal too fast. You are mostpresumptuous. You admit that all these occurrences tookplace when you were fast asleep, at a time when youcould not possibly have known anything about what wastaking place. How do you know that the laws of Nature arenot suspended during the night? It may be that there hasbeen some kind of supernatural interference in this case."In point of fact, he declares that your hypothesis is one ofwhich you cannot at all demonstrate the truth, and that youare by no means sure that the laws of Nature are the samewhen you are asleep as when you are awake.Well, now, you cannot at the moment answer that kindof reasoning. You feel that your worthy friend has yousomewhat at a disadvantage. You will feel perfectlyconvinced in your own mind, however, that you are quiteright, and you say to him, "My good friend, I can only beguided by the natural probabilities of the case, and if youwill be kind enough to stand aside and permit me to pass,I will go and fetch the police." Well, we will suppose thatyour journey is successful, and that by good luck you meetwith a policeman; that eventually the burglar is found withyour property on his person, and the marks correspond tohis hand and to his boots. Probably any jury wouldconsider those facts a very good experimental verificationof your hypothesis, touching the cause of the abnormalphenomena observed in your parlour, and would actaccordingly.Now, in this suppositious case, I have takenphenomena of a very common kind, in order that youmight see what are the different steps in an ordinaryprocess of reasoning, if you will only take the trouble toanalyse it carefully. All the operations I have described,you will see, are involved in the mind of any man of sensein leading him to a conclusion as to the course he shouldtake in order to make good a robbery and punish theoffender. I say that you are led, in that case, to yourconclusion by exactly the same train of reasoning as thatwhich a man of science pursues when he is endeavouringto discover the origin and laws of the most occultphenomena. The process is, and always must be, thesame; and precisely the same mode of reasoning wasemployed by Newton and Laplace in their endeavours to
discover and define the causes of the movements of theheavenly bodies, as you, with your own common sense,would employ to detect a burglar. The only difference is,that the nature of the inquiry being more abstruse, everystep has to be most carefully watched, so that there maynot be a single crack or flaw in your hypothesis. A flaw orcrack in many of the hypotheses of daily life may be oflittle or no moment as affecting the general correctness ofthe conclusions at which we may arrive; but, in a scientificinquiry, a fallacy, great or small, is always of importance,and is sure to be constantly productive of mischievous, ifnot fatal results.Do not allow yourselves to be misled by the commonnotion that an hypothesis is untrustworthy simply becauseit is an hypothesis. It is often urged, in respect to somescientific conclusion, that, after all, it is only an hypothesis.But what more have we to guide us in nine-tenths of themost important affairs of daily life than hypotheses, andoften very ill-based ones? So that in science, where theevidence of an hypothesis is subjected to the most rigidexamination, we may rightly pursue the same course. Youmay have hypotheses and hypotheses. A man may say, ifhe likes, that the moon is made of green cheese: that is anhypothesis. But another man, who has devoted a greatdeal of time and attention to the subject, and availedhimself of the most powerful telescopes and the results ofthe observations of others, declares that in his opinion it isprobably composed of materials very similar to those ofwhich our own earth is made up: and that is also only anhypothesis. But I need not tell you that there is anenormous difference in the value of the two hypotheses.That one which is based on sound scientific knowledge issure to have a corresponding value; and that which is amere hasty random guess is likely to have but little value.Every great step in our progress in discovering causeshas been made in exactly the same way as that which Ihave detailed to you. A person observing the occurrenceof certain facts and phenomena asks, naturally enough,what process, what kind of operation known to occur innature applied to the particular case, will unravel andexplain the mystery? Hence you have the scientifichypothesis; and its value will be proportionate to the careand completeness with which its basis had been testedand verified. It is in these matters as in the commonestaffairs of practical life: the guess of the fool will be folly,while the guess of the wise man will contain wisdom. In allcases, you see that the value of the result depends on thepatience and faithfulness with which the investigatorapplies to his hypothesis every possible kind ofverification.I dare say I may have to return to this point by-and-by;but having dealt thus far with our logical methods, I mustnow turn to something which, perhaps, you may considermore interesting, or, at any rate, more tangible. But inreality there are but few things that can be more importantfor you to understand than the mental processes and themeans by which we obtain scientific conclusions andtheories. 1 Having granted that the inquiry is a proper one,and having determined on the nature of the methods weare to pursue and which only can lead to success, I mustnow turn to the consideration of our knowledge of thenature of the processes which have resulted in the presentcondition of organic nature.Here, let me say at once, lest some of youmisunderstand me, that I have extremely little to report.The question of how the present condition of organicnature came about, resolves itself into two questions. Thefirst is: How has organic or living matter commenced itsexistence? And the second is: How has it beenperpetuated? On the second question I shall have more tosay hereafter. But on the first one, what I now have to saywill be for the most part of a negative character.If you consider what kind of evidence we can have uponthis matter, it will resolve itself into two kinds. We mayhave historical evidence and we may have experimentalevidence. It is, for example, conceivable, that inasmuch asthe hardened mud which forms a considerable portion ofthe thickness of the earth's crust contains faithful recordsof the past forms of life, and inasmuch as these differ moreand more as we go further down,—it is possible andconceivable that we might come to some particular bed orstratum which should contain the remains of thosecreatures with which organic life began upon the earth.And if we did so, and if such forms of organic life werepreservable, we should have what I would call historicalevidence of the mode in which organic life began uponthis planet. Many persons will tell you, and indeed you willfind it stated in many works on geology, that this has beendone, and that we really possess such a record; there aresome who imagine that the earliest forms of life of whichwe have as yet discovered any record, are in truth theforms in which animal life began upon the globe. The
forms in which animal life began upon the globe. Thegrounds on which they base that supposition are these:—That if you go through the enormous thickness of theearth's crust and get down to the older rocks, the highervertebrate animals—the quadrupeds, birds, and fishes—cease to be found; beneath them you find only theinvertebrate animals; and in the deepest and lowest rocksthose remains become scantier and scantier, not in anyvery gradual progression, however, until, at length, in whatare supposed to be the oldest rocks, the animal remainswhich are found are almost always confined to four forms—'Oldhamia', whose precise nature is not known, whetherplant or animal; 'Lingula', a kind of mollusc; 'Trilobites', acrustacean animal, having the same essential plan ofconstruction, though differing in many details from alobster or crab; and Hymenocaris, which is also acrustacean. So that you have all the 'Fauna' reduced, atthis period, to four forms: one a kind of animal or plant thatwe know nothing about, and three undoubted animals—two crustaceans and one mollusc.I think, considering the organization of these molluscaand crustacea, and looking at their very complex nature,that it does indeed require a very strong imagination toconceive that these were the first created of all livingthings. And you must take into consideration the fact thatwe have not the slightest proof that these which we callthe oldest beds are really so: I repeat, we have not theslightest proof of it. When you find in some places that inan enormous thickness of rocks there are but very scantytraces of life, or absolutely none at all; and that in otherparts of the world rocks of the very same formation arecrowded with the records of living forms, I think it isimpossible to place any reliance on the supposition, or tofeel oneself justified in supposing that these are the formsin which life first commenced. I have not time here to enterupon the technical grounds upon which I am led to thisconclusion,—that could hardly be done properly in half adozen lectures on that part alone;—I must content myselfwith saying that I do not at all believe that these are theoldest forms of life.I turn to the experimental side to see what evidence wehave there. To enable us to say that we know anythingabout the experimental origination of organization and life,the investigator ought to be able to take inorganic matters,such as carbonic acid, ammonia, water, and salines, inany sort of inorganic combination, and be able to buildthem up into Protein matter, and that that Protein matterought to begin to live in an organic form. That, nobody hasdone as yet, and I suspect it will be a long while beforeanybody does do it. But the thing is by no means soimpossible as it looks; for the researches of modernchemistry have shown us—I won't say the road towards it,but, if I may so say, they have shown the finger-postpointing to the road that may lead to it.It is not many years ago—and you must recollect thatOrganic Chemistry is a young science, not above a coupleof generations old,—you must not expect too much of it; itis not many years ago since it was said to be perfectlyimpossible to fabricate any organic compound; that is tosay, any non-mineral compound which is to be found in anorganized being. It remained so for a very long period; butit is now a considerable number of years since adistinguished foreign chemist contrived to fabricate Urea,a substance of a very complex character, which forms oneof the waste products of animal structures. And of lateyears a number of other compounds, such as Butyric Acid,and others, have been added to the list. I need not tell youthat chemistry is an enormous distance from the goal Iindicate; all I wish to point out to you is, that it is by nomeans safe to say that that goal may not be reached oneday. It may be that it is impossible for us to produce theconditions requisite to the origination of life; but we mustspeak modestly about the matter, and recollect thatScience has put her foot upon the bottom round of theladder. Truly he would be a bold man who would ventureto predict where she will be fifty years hence.There is another inquiry which bears indirectly upon thisquestion, and upon which I must say a few words. You areall of you aware of the phenomena of what is calledspontaneous generation. Our forefathers, down to theseventeenth century, or thereabouts, all imagined, inperfectly good faith, that certain vegetable and animalforms gave birth, in the process of their decomposition, toinsect life. Thus, if you put a piece of meat in the sun, andallowed it to putrefy, they conceived that the grubs whichsoon began to appear were the result of the action of apower of spontaneous generation which the meatcontained. And they could give you receipts for makingvarious animal and vegetable preparations which wouldproduce particular kinds of animals. A very distinguishedItalian naturalist, named Redi, took up the question, at atime when everybody believed in it; among others our own
great Harvey, the discoverer of the circulation of the blood.You will constantly find his name quoted, however, as anopponent of the doctrine of spontaneous generation; butthe fact is, and you will see it if you will take the trouble tolook into his works, Harvey believed it as profoundly asany man of his time; but he happened to enunciate a verycurious proposition—that every living thing came from an'egg'; he did not mean to use the word in the sense inwhich we now employ it, he only meant to say that everyliving thing originated in a little rounded particle oforganized substance; and it is from this circumstance,probably, that the notion of Harvey having opposed thedoctrine originated. Then came Redi, and he proceeded toupset the doctrine in a very simple manner. He merelycovered the piece of meat with some very fine gauze, andthen he exposed it to the same conditions. The result ofthis was that no grubs or insects were produced; heproved that the grubs originated from the insects whocame and deposited their eggs in the meat, and that theywere hatched by the heat of the sun. By this kind of inquiryhe thoroughly upset the doctrine of spontaneousgeneration, for his time at least.Then came the discovery and application of themicroscope to scientific inquiries, which showed tonaturalists that besides the organisms which they alreadyknew as living beings and plants, there were an immensenumber of minute things which could be obtainedapparently almost at will from decaying vegetable andanimal forms. Thus, if you took some ordinary blackpepper or some hay, and steeped it in water, you wouldfind in the course of a few days that the water had becomeimpregnated with an immense number of animalculesswimming about in all directions. From facts of this kindnaturalists were led to revive the theory of spontaneousgeneration. They were headed here by an Englishnaturalist,—Needham,—and afterwards in France by thelearned Buffon. They said that these things wereabsolutely begotten in the water of the decayingsubstances out of which the infusion was made. It did notmatter whether you took animal or vegetable matter, youhad only to steep it in water and expose it, and you wouldsoon have plenty of animalcules. They made anhypothesis about this which was a very fair one. Theysaid, this matter of the animal world, or of the higherplants, appears to be dead, but in reality it has a sort ofdim life about it, which, if it is placed under fair conditions,will cause it to break up into the forms of these littleanimalcules, and they will go through their lives in thesame way as the animal or plant of which they onceformed a part.The question now became very hotly debated.Spallanzani, an Italian naturalist, took up opposite viewsto those of Needham and Buffon, and by means of certainexperiments he showed that it was quite possible to stopthe process by boiling the water, and closing the vessel inwhich it was contained. "Oh!" said his opponents; "butwhat do you know you may be doing when you heat theair over the water in this way? You may be destroyingsome property of the air requisite for the spontaneousgeneration of the animalcules."However, Spallanzani's views were supposed to beupon the right side, and those of the others fell intodiscredit; although the fact was that Spallanzani had notmade good his views. Well, then, the subject continued tobe revived from time to time, and experiments were madeby several persons; but these experiments were notaltogether satisfactory. It was found that if you put aninfusion in which animalcules would appear if it wereexposed to the air into a vessel and boiled it, and thensealed up the mouth of the vessel, so that no air, savesuch as had been heated to 212 degrees, could reach itscontents, that then no animalcules would be found; but ifyou took the same vessel and exposed the infusion to theair, then you would get animalcules. Furthermore, it wasfound that if you connected the mouth of the vessel with ared-hot tube in such a way that the air would have to passthrough the tube before reaching the infusion, that thenyou would get no animalcules. Yet another thing wasnoticed: if you took two flasks containing the same kind ofinfusion, and left one entirely exposed to the air, and in themouth of the other placed a ball of cotton wool, so that theair would have to filter itself through it before reaching theinfusion, that then, although you might have plenty ofanimalcules in the first flask, you would certainly obtainnone from the second.These experiments, you see, all tended towards oneconclusion—that the infusoria were developed from littleminute spores or eggs which were constantly floating inthe atmosphere, which lose their power of germination ifsubjected to heat. But one observer now made anotherexperiment which seemed to go entirely the other way,and puzzled him altogether. He took some of this boiled
and puzzled him altogether. He took some of this boiledinfusion that I have been speaking of, and by the use of amercurial bath—a kind of trough used in laboratories—hedeftly inverted a vessel containing the infusion into themercury, so that the latter reached a little beyond the levelof the mouth of the 'inverted' vessel. You see that he thushad a quantity of the infusion shut off from any possiblecommunication with the outer air by being inverted upon abed of mercury.He then prepared some pure oxygen and nitrogengases, and passed them by means of a tube going fromthe outside of the vessel, up through the mercury into theinfusion; so that he thus had it exposed to a perfectly pureatmosphere of the same constituents as the external air.Of course, he expected he would get no infusorialanimalcules at all in that infusion; but, to his great dismayand discomfiture, he found he almost always did get them.Furthermore, it has been found that experiments madein the manner described above answer well with mostinfusions; but that if you fill the vessel with boiled milk, andthen stop the neck with cotton-wool, you 'will' haveinfusoria. So that you see there were two experiments thatbrought you to one kind of conclusion, and three toanother; which was a most unsatisfactory state of things toarrive at in a scientific inquiry.Some few years after this, the question began to be veryhotly discussed in France. There was M. Pouchet, aprofessor at Rouen, a very learned man, but certainly not avery rigid experimentalist. He published a number ofexperiments of his own, some of which were veryingenious, to show that if you went to work in a properway, there was a truth in the doctrine of spontaneousgeneration. Well, it was one of the most fortunate things inthe world that M. Pouchet took up this question, because itinduced a distinguished French chemist, M. Pasteur, totake up the question on the other side; and he hascertainly worked it out in the most perfect manner. I amglad to say, too, that he has published his researches intime to enable me to give you an account of them. Heverified all the experiments which I have just mentioned toyou—and then finding those extraordinary anomalies, asin the case of the mercury bath and the milk, he set himselfto work to discover their nature. In the case of milk hefound it to be a question of temperature. Milk in a freshstate is slightly alkaline; and it is a very curiouscircumstance, but this very slight degree of alkalinityseems to have the effect of preserving the organismswhich fall into it from the air from being destroyed at atemperature of 212 degrees, which is the boiling point. Butif you raise the temperature 10 degrees when you boil it,the milk behaves like everything else; and if the air withwhich it comes in contact, after being boiled at thistemperature, is passed through a red-hot tube, you will notget a trace of organisms.He then turned his attention to the mercury bath, andfound on examination that the surface of the mercury wasalmost always covered with a very fine dust. He found thateven the mercury itself was positively full of organicmatters; that from being constantly exposed to the air, ithad collected an immense number of these infusorialorganisms from the air. Well, under these circumstanceshe felt that the case was quite clear, and that the mercurywas not what it had appeared to M. Schwann to be,—a barto the admission of these organisms; but that, in reality, itacted as a reservoir from which the infusion wasimmediately supplied with the large quantity that had sopuzzled him.But not content with explaining the experiments ofothers, M. Pasteur went to work to satisfy himselfcompletely. He said to himself: "If my view is right, and if,in point of fact, all these appearances of spontaneousgeneration are altogether due to the falling of minutegerms suspended in the atmosphere,—why, I ought notonly to be able to show the germs, but I ought to be able tocatch and sow them, and produce the resultingorganisms." He, accordingly, constructed a very ingeniousapparatus to enable him to accomplish this trapping of this"germ dust" in the air. He fixed in the window of his room aglass tube, in the centre of which he had placed a ball ofgun-cotton, which, as you all know, is ordinary cotton-wool, which, from having been steeped in strong acid, isconverted into a substance of great explosive power. It isalso soluble in alcohol and ether. One end of the glasstube was, of course, open to the external air; and at theother end of it he placed an aspirator, a contrivance forcausing a current of the external air to pass through thetube. He kept this apparatus going for four-and-twentyhours, and then removed the 'dusted' gun-cotton, anddissolved it in alcohol and ether. He then allowed this tostand for a few hours, and the result was, that a very finedust was gradually deposited at the bottom of it. That dust,on being transferred to the stage of a microscope, was
found to contain an enormous number of starch grains.You know that the materials of our food and the greaterportion of plants are composed of starch, and we areconstantly making use of it in a variety of ways, so thatthere is always a quantity of it suspended in the air. It isthese starch grains which form many of those brightspecks that we see dancing in a ray of light sometimes.But besides these, M. Pasteur found also an immensenumber of other organic substances such as spores offungi, which had been floating about in the air and had gotcaged in this way.He went farther, and said to himself, "If these really arethe things that give rise to the appearance of spontaneousgeneration, I ought to be able to take a ball of this 'dusted'gun-cotton and put it into one of my vessels, containingthat boiled infusion which has been kept away from theair, and in which no infusoria are at present developed,and then, if I am right, the introduction of this gun-cottonwill give rise to organisms."Accordingly, he took one of these vessels of infusion,which had been kept eighteen months, without the leastappearance of life, and by a most ingenious contrivance,he managed to break it open and introduce such a ball ofgun-cotton, without allowing the infusion or the cotton ballto come into contact with any air but that which had beensubjected to a red heat, and in twenty-four hours he hadthe satisfaction of finding all the indications of what hadbeen hitherto called spontaneous generation. He hadsucceeded in catching the germs and developingorganisms in the way he had anticipated.It now struck him that the truth of his conclusions mightbe demonstrated without all the apparatus he hademployed. To do this, he took some decaying animal orvegetable substance, such as urine, which is an extremelydecomposable substance, or the juice of yeast, or perhapssome other artificial preparation, and filled a vessel havinga long tubular neck with it. He then boiled the liquid andbent that long neck into an S shape or zig-zag, leaving itopen at the end. The infusion then gave no trace of anyappearance of spontaneous generation, however long itmight be left, as all the germs in the air were deposited inthe beginning of the bent neck. He then cut the tube closeto the vessel, and allowed the ordinary air to have free anddirect access; and the result of that was the appearance oforganisms in it, as soon as the infusion had been allowedto stand long enough to allow of the growth of those itreceived from the air, which was about forty-eight hours.The result of M. Pasteur's experiments proved, therefore,in the most conclusive manner, that all the appearances ofspontaneous generation arose from nothing more than thedeposition of the germs of organisms which wereconstantly floating in the air.To this conclusion, however, the objection was made,that if that were the cause, then the air would contain suchan enormous number of these germs, that it would be acontinual fog. But M. Pasteur replied that they are notthere in anything like the number we might suppose, andthat an exaggerated view has been held on that subject;he showed that the chances of animal or vegetable lifeappearing in infusions, depend entirely on the conditionsunder which they are exposed. If they are exposed to theordinary atmosphere around us, why, of course, you mayhave organisms appearing early. But, on the other hand, ifthey are exposed to air from a great height, or from somevery quiet cellar, you will often not find a single trace of.efilSo that M. Pasteur arrived at last at the clear anddefinite result, that all these appearances are like the caseof the worms in the piece of meat, which was refuted byRedi, simply germs carried by the air and deposited in theliquids in which they afterwards appear. For my own part, Iconceive that, with the particulars of M. Pasteur'sexperiments before us, we cannot fail to arrive at hisconclusions; and that the doctrine of spontaneousgeneration has received a final 'coup de grace'.You, of course, understand that all this in no wayinterferes with the 'possibility' of the fabrication of organicmatters by the direct method to which I have referred,remote as that possibility may be.1 (return)[e nTdheoasveo uwrheod  twoi sghi vteo  sstoumdey  rfuolulyg ht haen dd orcetaridnye sil luofs trwahtiiocnh s,I  hmauvsetread Mr. John Stuart Mill's 'System of Logic'.]
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