SPRING QUARTER, 2006
Department of History
University of California, Irvine
Instructor: Dr. Barbara J. Becker
Week 8. Behavior excerpts from
|
I.
appeared in Nature September 22, 1870
SPEAKING with all the authority which years of earnest and successful labour have conferred, and, moreover, "from the elevation upon which the suffrages of his colleagues had for the time placed him," Prof. Huxley has just given us in his Inaugural Address, as President of the British Association for the Advancement of Science, a "history of the rise and progress of a single biological doctrine" -- that first proclaimed by Francesco Redi, and to the effect that Every living thing proceeds from a pre-existing living thing.
However reluctant to enter a protest against what has been said by an eminent scientific man, for whom I have always entertained the greatest respect and esteem, I feel so strongly that the representations which have been made concerning a subject to which I have directed the most earnest attention for the last eighteen months, are not only inadequate, but altogether incapable of being regarded as an impartial statement of the main points at issue, that I cannot hesitate as to the propriety of publicly expressing this opinion.
Fearful, therefore, lest harm should be done to the cause of science by this address, through the great influence of the speaker, and mindful of the momentous issues which turn upon the proper solution of the question under discussion, I -- sinking all personal feelings, risking all imputations, anxious only that the truth should be known -- will venture to state what really seems to me to be the true aspect of the problem, and how far the remarks of Prof. Huxley really bear upon this, or have been in other respects, not sufficiently explicit.
The doctrine, whose history Prof. Huxley professes to trace, and whose probable truth he thinks remains unshaken, has reference to a question which is of more fundamental importance than any other throughout the whole range of Biological science. It is either true that all living matter, without exception, comes into being in connection with pre-existing living matter, or else it is true that some living matter can arise from non-living materials free from all connection with pre-existing living matter. This alternative is one the full meaning of which may, perhaps be realised better by putting another, which, though strictly analogous, is somewhat freer from mystery. It may, then, similarly be said, it is either true that all crystalline matter, without exception, comes into being in connection with pre-existing crystalline matter, or else it is true that some crystalline matter can arise from non-crystalline materials, free from all connection with pre-existing crystalline matter. Matter when it passes into the crystalline condition exhibits properties of a certain kind, and when it passes into the living condition it exhibits properties of another kind, to which we commonly apply the term "vital." Now the question in each case is, whether by mere concurrence of certain physical conditions, aiding and abetting the inherent properties of the matter itself, some kinds of matter can fall into modes of combination called crystalline, whilst other kinds are capable of falling into modes of combination called living; or whether, in each case, a pre-existing "germ" of the particular kind of matter is necessary, in order to determine, in suitable media, either of these modes of combination. Are we to believe that crystals can appear in no solution whatsoever without the pre-existence in that solution of certain crystalline germs, and similarly that living things can arise in no solution whatsoever without the pre-existence in such solution of living germs? To many persons it may at first sight seem that there is no analogy between the two cases; such, however, is not the opinion of very many who are best entitled to speak on the subject. It is admitted by them that the analogy is of the closest description; and it is interesting to note that although the actual evidence which can be brought to bear upon these two questions is very similar in kind, and alike conflicting in nature, the generally received opinions as regards the proper answers to be given to these two questions have inclined to the view that, whilst it is possible for crystals to originate de novo, it is at present impossible for living things to originate after this fashion.
The question is one of much interest, and it may therefore well be asked why such a totally different verdict should have been given in two cases, the analogy of which is so remarkable. The reason is, however, not difficult to find. Mere theoretical considerations have been all-powerful in influencing the verdict, and in inducing those who are informed upon the subject to read the evidence in different ways. Living things manifest such complex properties that the whole notion of Life has been shrouded in mystery. Biologists at first could not bring themselves to believe -- some cannot do so now -- that the phenomena which living things manifest are absolutely dependent upon the properties of the variously organised matter entering into their composition. They were obliged to have recourse to some metaphysical entity -- some "anima," "archæus," or "vital principle" -- under whose directing influence the living form was supposed to be built up, and upon whose persisting influence many of the phenomena of Life were supposed to depend. The aid of no similar metaphysical "principle" has, however, been deemed necessary in order to account for crystalline structures and properties. It was in the main conceded by most physicists, and the doctrine remained unquestioned by biologists, that matter of certain kinds might, by virtue of its own inherent properties, aided by certain favouring circumstances -- and quite independently of all pre-existing germs -- fall into such modes of collocation as to give rise to crystals. But, owing to the influence of the theoretical considerations already mentioned concerning the nature of Life, a similar possibility could not easily be granted in reference to the origin of Living things. Was it not held that the living thing owed its structure or organisation to the active influence of a special and peculiar principle? This "vital principle" was neither ordinary matter nor ordinary force, neither was it in any way derivable from either of these; how then could it be supposed that the coming together of matter of any kind could give rise to a living thing?*
| [*Buffon, it is true, as Professor Huxley has pointed out, did make an attempt to reconcile two incompatible theories.] |
The aggregate of properties, which we designate by the word, "Life," were not supposed to be dependent up, to be, in fact, properties of the material aggregate which constituted the Living thing. Life was presumed to be due to the manifestations of a something altogether peculiar -- of a "vital principle," which was inseparable from living matter. Doctrines akin to these having been already proclaimed and disseminated by the influential teachings of Paracelsus, Van Helmont, and others, it cannot be a matter for surprise that the brilliant demonstrations of Redi should have had a great influence in their time. Observation after observation appeared now to confirm the existence of a seemingly universal mode of origin of Living things -- a mode too which was more in harmony with the philosophical views of the day than that which had hitherto been deemed possible. Doubts, however, soon spring up. New means of observation opened up new questions for solution. And what has been the result? Many battles have been fought, many victories have been won, and now the biological doctrines of the day have assumed an entirely new form. The ever-increasing strides of Science have wrought the most fundamental changes in our notions concerning Life. Under the influence of the well-established doctrine concerning Persistence of Force -- and more especially since the clear recognition of the subordinate doctrine as to the Correlation existing between the Physical and Vital forces -- physiologists have now begun to recognise, and most unhesitatingly to express the opinion, that the phenomena manifested by living things are to be ascribed simply to the properties of the matter as it exists in such living things. No one has expressed himself more decidedly on this subject than Prof. Huxley himself, and he may fairly be taken as an exponent of the modern doctrines on this question. He says:
"Carbon, hydrogen, oxygen, and nitrogen are all lifeless bodies. Of these, carbon and oxygen unite in certain proportions and under certain conditions to give rise to carbonic acid; hydrogen and oxygen produce water; nitrogen and hydrogen give rise to ammonia. These new compounds, like the elementary bodies of which they are composed, are lifeless. But when they are brought together under certain conditions they give rise to the still more complex body, protoplasm; and this protoplasm exhibits the phenomena of life. I see no break in this series of steps in molecular complication, and I am unable to understand why the language, which is applicable to any one term of the series, may not be used to any of the others. We think fit to call different kinds of matter carbon, oxygen, hydrogen, and nitrogen; and to speak of the various powers and activities of these substances as the properties of the matter of which they are composed.... Is the case in any way changed when carbonic acid water and ammonia disappear, and in their place, under the influence of pre-existing protoplasm, an equivalent weight of the matter of Life makes its appearance?... What justification is there then for the assumption of the existence in the Living matter of a something which has no representative or correlative in the not-living matter which gave rise to it?"*
| [*Fortnightly Review, Feb. 1869.] |
For Professor Huxley, then, and for all who hold similar opinions on this subject, the constitution and properties of living things are so far comparable with the constitution and properties of crystals, that both, in each case, are alike supposed to be the products of the combination of ordinary matter of different kinds. And, as might have been expected, nearly all the biologists and physicists who hold these opinions, are now inclined to admit their belief in the possibility of the origination of living matter free from the influence, and independently, of all pre-existing living matter. They are quite content to admit that Redi's doctrine may be wrong. Prof. Huxley, indeed, in his recent address, desires us to understand that this is an opinion to which he still adheres: he says: -- "I think it would be the height of presumption for any man to say that the conditions under which matter assumes the properties we call 'vital,' may not some day be artificially brought together."
Having reached this stage, having got rid of the supposed necessity for the intervention of a special "vital principle" before living matter can come into existence,* I think it will be seen by all how very important it has become to look into the truth of Redi's doctrine, which has found its best modern expression in the phrase omne vivum ex vivo, seeing that that doctrine was born and nourished under the influence of the old, and now well-night effect, metaphysical notions concerning Life. Certainly, now that this theoretical barrier has been removed, we ought to inquire more carefully than ever whether there is still a sufficient warrant for the different verdicts which have been given in answer to the questions as to whether crystals on the one hand, or living things on the other, do or do not originate de novo in this particular stage of the Earth's history.
| [*It may perhaps be as well to state here that I have not much expectation of influencing those whose belief in the existence of a special "vital principle" remains still unshaken.] |
Now, at all events, theory inclines no more to the one side than it does to the other; it is quite possible to reconcile this with either view.
Seeing, therefore, that we may now act without fear as impartial judges, let us inquire into the nature of the evidence which alone can be relied upon for the solution of these two questions. If living things are to come into being de novo, they could, or, at all events, are only supposed to originate from the rearrangement of matter which previously existed in a state of solution. And although it is known to be possible for certain kinds of pre-existing solid matter to assume a crystalline form, we will, for the present, confine our attention to the origin of crystals in an apparently homogeneous fluid. Each of these material forms, therefore, would have to commence as a smallest conceivable speck, and each would grow, though differently, by the formation of matter of like kind, under influences generally similar to those which were influential in bringing about the primordial collocation. These primordial collocations, however, are hidden from our view, and will, perhaps for ever, remain so. As a matter of observation, all that we actually know concerning the origin of crystals or of certain living things in solutions is this. In previously homogeneous solutions of crystallisable matter, or in certain apparently homogeneous colloidal solutions, we may, under certain conditions, see the minutest crystals or living things, respectively, make their appearance.. In both cases these are, at first, mere motionless specks, whose minimum visible stage may be les than 1/100000th of an inch in diameter. It must either be presumed, in the case of such embryo living things (as most people do presume in the case of crystals), that these even then, and however minute, represent stages in the growth of later material collocations which had been initiated under the combined influence of existing matter and "conditions" at a point far beyond the reach of our most aided vision; or, on the other hand, it is equally open for us to suppose that such minutest visible living things had proceeded form the growth of pre-existing germs which were themselves invisible.
This being, as I conceive, the real state of the case, and Professor Huxley being in the position of a person, admitting* that a crystal can be produced de novo, admitting also the possibility that a living thing may so arise, but denying that there is any evidence worthy of serious consideration to show that a living thing can at the present time originate de novo, let us see on what evidence he has come to this conclusion, and what other evidence he has practically ignored.
| [*I suppose this may fairly enough be presumed even in the absence of nay specific statement as to his belief on the subject. This is, however, an assumption on my part.] |
In the first place, he does not attempt to deny -- he does not even allude to the fact -- that Living things may and do arise as minutest visible specks, in solutions in which, but a few hours before, no such specks were to be seen. And this is in itself a very remarkable omission. The statement must be true or false, and if true, as I and others affirm, the question, which Professor Huxley has set himself to discuss, is no longer one of such a simple nature as he represents it to be. It is henceforth settled so far as visible germs are concerned, that living things can come into being without them., It can now, at all events, be said that some Living things do not come from visible germs. Who, therefore, in the face of this fact will say that the doctrine omne vivum ex vivo remains unshaken? Perhaps, however, this particular case where an exception to the rule is possible, was not known to Professor Huxley. I wish I could bring myself to believe that this was really the case. Certain it is that he had recognised the existence of this apparent exception to the general rule he would then have had to discuss a much more difficult question, and he would have been compelled seriously to inquire into the value of experiments whose existence he has now almost ignored. Again then I affirm that multitudes of minute living things may and do gradually appear in fluids, beneath the microscope, where no visible germs previously existed. Here the hypothesis that every living thing proceeds from a pre-existing living thing may break down, and those who wish to establish the continuity of this rule are bound to discuss the nature of the existing evidence which is in favour of the notion of the living things in question originating from pre-existing invisible germs, as against the opposite possibility of their having originated de novo. The burden of proof rests as much on the one side as it rests on the other. We cannot safely continue to affirm a rule until the cases in which it seems doubtful have been thoroughly discussed. Analogy is often but a treacherous guide.
And, when we come to the discussion of this hypothesis as to the origin of living things from germs which are invisible, all alike are rendered, to a certain extent, helpless. No one, then, can come forward, as Redi is said to have done, "strong with the sense of demonstrable fact," and any one who wishes or calls upon his opponent to demonstrate the truth of his views, when the question is one concerning the presence of absence of invisible germs, shows himself to be ignorant as to how the matter in dispute can alone be settled. The subject is one in which direct demonstration must give place to reasoning, although experiment and observation may and must be brought forward in support of this. Let those, however, who wish to proclaim the universality of the rule omne vivum ex vivo, recollect that, if they expect to influence reasonable people who are themselves competent to form an opinion on the subject, they are bound to consider the possible exception to which their attention is directed, and to weigh the evidence for and against the origin of these minutest visible living specks from germs which are supposed to exist, but which are invisible.
The reason, indeed, which seems to induce most people to believe that living things cannot arise de novo, is because in 999 cases out of a thousand which come under their actual notice, there cannot be a question that a living thing originates from a pre-existing living thing. A rule, which is of such apparently universal application, they say, is most likely to be the rule which applies to any doubtful case. Much is made out of this argument, which is, of course, a very valid one so far as it goes. But, on the other hand, knowing, as I have pointed out, that any living things which arise, de novo, from non-living matter, must appear in solutions as minutest visible specks, it need not be a matter of much surprise that this mode of generation is one which is unfamiliar to the world at large. Have we not seen, indeed, that the most accomplished biologist, provided with the very best microscope hitherto made, though he gets down to a minimum visible stage of less than 1/100000" in diameter is just as powerless in face of the hypothesis of invisible germs as those who worked with the rude microscopes which alone were in vogue two centuries ago? And, more especially is this consideration one which presses for earnest attention, when we further consider that some of the minute living things which first appear as tiniest specks in homogeneous solutions grow into Bacteria, and that concerning the real origin of these, in such cases, we are as ignorant as we were concerning the real origin of crystals, when they appeared in previously homogeneous solutions. The probability that these latter have originated de novo has, of late years, had to be established by a process of reasoning similar to what we are obliged to have recourse to, if we wish to throw light on the question of the origin of these specks of Living matter. Bacteria grow, and after a time aggregations of them may be converted under our very eyes into Fungus-spores capable of throwing out a filaments and of developing into perfect plants. Nobody pretends to know, however, how, or whether the Bacteria which make their appearance in a homogeneous solution have originated from invisible Fungus-emanations: all that we know is, that in suitable solutions, appearing homogeneous to high microscopic powers, in the course of a very short time, a multitude of perfectly motionless specks appear, in situations where previously no specks had existed. Being motionless and diffused their number cannot be accounted for by any supposed rapidity of multiplication -- the only possible explanations seem to be, either that the specks have originated from as many pre-existing germs which were invisible, or else that they have proceeded from material collocations, which have been initiated in the fluid itself by virtue of the molecular properties of the substances in solution, and the physical forces or sum total of "conditions," acting thereupon.
And this is really the question which has to be considered. When it is supposed that Living things do appear independently of pre-existing living matter, in certain solutions nothing more than this is supposed to have taken place. New Living matter is presumed to have appeared -- independently of germs -- in the solutions within these flasks, and to have made its appearance as living matter may, in certain other fluids, under our very eyes, in the form of minutest visible specks, which have been exposed to great and long-continued heat in hermetically sealed masses. And similarly such specks, are the only forms of Living matter which are supposed to be capable of arising de novo. Once formed, it is true, one of these living specks may develop into a Bacterium, and this may develop into a Vibrio or a Leptothrix filament, whilst another of the living specks may develope at once into a Fungus-spore. It should be clearly understood, however, that all the Living things which are supposed to arise out of no-living materials, are presumed to appear in fluids, and gradually to emerge from the region of the invisible into that of the visible; at which latter point they, for us, constitute specks less than 1/100000" in diameter.
Making no statements whatever upon this subject however, in support of the doctrine which he considers to remain unshaken, let us see what line of argument Professor Huxley has taken, in order to establish the validity of this belief to the members of the British Association for the Advancement of Science.
The "long chain of evidence" which he considers sufficient to allow us still to place faith in the rule omne vivum ex vivo, seems to me, to be, in reality, utterly inadequate for this purpose, and incapable of affecting the real question at issue. Nothing that has been said bears at all upon the problem as to whether it is possible that the minute living specks to which I have referred do or do not originate de novo, though, as I have already said, it is these, and such as these only, which are presumed to originate after this fashion. If he had really wished to influence those who are conversant with the subject, it would have been absolutely imperative for Prof. Huxley to have entered fully into the consideration of a subject which I shall presently mention, but to which he makes only the most casual allusion. All the facts which he has brought forward -- all the references to the investigations of Spallanzani, Schultze and Schwann [etc.] -- are simply contributions to the "Atmospheric Germ Theory," tending to show that there are germs of living things in the air, and that the living things found in some solutions may have been developed therefrom. But although differing from him in my interpretation of the results of some of these investigations, I am quite content to accept the conclusion which is alone derivable from this long chain of evidence. I am even prepared to grant to Professor Huxley, for the sake of argument, that Bacteria may be "suspended in the atmosphere in myriads." The evidence thus referred to, if true in all respects, would have been very valuable if it had been brought against the doctrine that none of the minute living beings of infusions derived their origin from atmospheric germs, though it may and does fall utterly powerless before the doctrine which is alone urged, that some of the Living things met with in infusions appear to be produced independently of pre-existing living mater. If it could be proved that the air contained five hundred times as many germs as can now be shown to exist therein, this discovery would still be quite compatible with the truth of the other doctrine that under the influence of certain conditions some Living things, appearing as minutest visible specks, do arise de novo in solutions....
II.
appeared in Nature September 29, 1870
...So far as all direct experiment and observation has hitherto gone, no Living thing whatsoever has been found to survive in a fluid which has been exposed for two or three minutes to a temperature of 110°C. And if we couple this fact with a due consideration of the fundamental unity in nature of all Living matter, the supposition that any Living things -- found in solutions that had been submitted to a far greater heat for two, three, or four hours -- had braved this heat with impunity, would be an assumption seemingly much more improbable than the only possible counter supposition, viz, that the Living things had been evolved de novo. The former supposition would be less likely to be true, because, instead of being consistent or harmonising with our general knowledge, it would seem to be a mere isolated fact bearing n its face the impress of grave improbability. Bacteria and fungus-spores which cannot, when made the subject of direct observation, resist the influence of a lower temperature, are, however to be supposed capable of resisting the influence of a much higher temperature when their behaviour is watched by no human eye, though at a juncture when human prejudice emphatically requires that they should do so. This extreme improbability -- this isolated and otherwise unsupported notion -- is cherished, whilst the other supposition, which is consistent with direct observation so far as it can go, and which is thoroughly in harmony with a great mass of scientific truth, is rejected. And why is it rejected? Because it is alleged that a great mass of human experience, having no immediate bearing upon this particular subject, and which is only related thereto by analogy, seems to make it improbable....
Having visited one of the largest [canning] establishments in London and seen the whole process to which the meats and vegetables are submitted for preservation, the information I have to convey is of the most authentic description....
A number of cases, enclosing the provisions, instead of being simply heated to a temperature of 212°F. as most people would understand from what Prof. Huxley said, are first heated in a large chloride of calcium bath (warmed by steam) to a temperature of 230° to 235°F. for more than an hour and a half. The hole through which the steam has been issuing is then closed with solder, and as soon as the last of the set has been thus hermetically sealed, a higher pressure of steam is turned on, by which the bath is quickly raised to a temperature of from 258° to 260°C. -- at which temperature it is maintained for more than half an hour.... Now, on inquiry, it appears that the number of unmistakable failures even in the very best establishments is very appreciable, and although many of these failures may be accounted for by defective closure, Mr. McCall assured me that in a certain number of cases, where not the smallest defect could be detected in the tin, where the mode of preparation was unexceptionable, and the provisions originally of the best description, yet for some inscrutable reason some of these tins did prove utter failures. Gas was found to be evolved within, causing them to bulge at the extremities, and when opened the meats either showed a central decomposition of a most foetid character without mould, or lese mould might be found on some portions of the surface. He further assured me that certain tins which had been thoroughly well prepared, and in which the provisions seemed to remain in a perfect state of preservation for tow or even three years, might more or less suddenly show signs of a considerable evolution of gas within, owing to the provisions having fallen into a state of putrefaction. In other instances provisions would keep for ten years or more without any appreciable change.... Mr. McCall was somewhat doubtful as to whether in hot weather, provisions were more prone to fail after severe thunder storms. He had, however, "often thought that electricity" had something to do with the failures. Some of the large retail sellers spoke much more decidedly to me as to the number of failures after thunder. On this question, however, I lay no stress -- I merely repeat what I was told.
Wishing to learn what microscopical appearances would be presented by provisions which were sold as being "perfectly good," I procured three specimens from two of the most esteemed retail establishments.... [These] specimens which I have examined microscopically ... all presented evidences that Living things had been growing and developing in the hermetically sealed tins. Why, in some cases, the changes should be so small in extent as not to impair the value of the provisions, and in other cases ... render the provisions utterly useless, I, or others holding similar opinions, can scarcely be called upon fully to explain. Certain it is, however that the facts above mentioned, including the circumstance that the failures sometimes take place after the tins have been hermetically sealed for two or three years, and that gelatinous substances are the least prone to change -- are all rather strongly in favour of my view of the case, and will continue to be so, so long as our knowledge concerning the inability of Living things to resist the destructive influence of very high temperatures remains in anything like the same condition as it is at the present day....
I should like to ask [Prof. Huxley] whether he considers it the function of a scientific investigator to believe only in such seeming possibilities as he can at the time explain or account for.... Prof. Huxley seems only too much to overlook the fact that what may be perfectly inexplicable from one point of view, may, on the contrary, flow as a necessary consequence from one of an opposite nature.... [H]aving two doctrines of almost equal probability to decide between, it seems to me mere childishness to reject a certain well-supported interpretation simply because it is inexplicable on the one hypothesis, and to think that this inexplicability is an argument against the interpretation given, when, so far from being inexplicable, this, in the light of the counter hypothesis, is nothing else than a logical consequence.... I entirely agree with Mr. G. H. Lewes [English philosopher and literary critic, George Henry Lewes (1817-1878)], when ... he points out that "similarity in the laws and conditions of Organic Combination must produce similarity in organisms, independently of relationship, just as similarity in the laws and conditions of inorganic combination will produce identity in chemical species."*
| [*"Darwin's Hypothesis" Fortnightly Review, April 1868, p. 372. |
It is the extreme complexity of the materials in the one case, and their corresponding sensitiveness to modifying influences, which make it hopeless for us to think of ever getting the same uniformity of results, which we are able to attain when we have to do with simple inorganic materials. The difference, however, is one of degree, not kind.
I enter a protest, therefore, against the first portion of Prof. Huxley's Inaugural Address, for the following reasons: --
1. Because it does not seem to be characterised by "due impartiality."
2. Because it is calculated to mislead the public; since what is represented as relevant and of first importance, has only an indirect bearing on the subject: Abundance or paucity of germs in atmosphere.
3. Because the real issues having already been pointed out by others, Prof. Huxley ignoring these, approaches the problem as though they had never been stated, and as though he himself were not aware of them: Mode of origin of specks of Living matter in apparently homogeneous solutions.
4. Because it allows room for the inference, and even suggests it, that evidence which is generally admitted to be of the greatest importance for the solution of the question in dispute, is really of little or no importance: Limits of vital resistance to heat, and presence of Living organisms in closed vessels which had been previously exposed to great heat.
5. Because, without any sufficient warrant, it throws doubt upon the "trustworthiness" of certain experiments, of whose real nature his audience and the public are not informed: Experiments of Wyman, Mantegazza, Cantoni, &c.
6. Because it opposes the definite results of these experiments by nothing but insufficient statements, and what appear to be crude suppositions: Statements and assumptions concerning preserved meats.
The general effect being, I conceive, an entire misrepresentation of the present state of knowledge upon the questions concerning the Origin of Life, which are at present under discussion.
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