An historian of the founders of modern astronomy recently related that the philosopher Cleanthus, three millennia before our era, wished to prosecute Aristarchus for blasphemy, for having believed that the earth moved, and having dared to say that the sun was the immovable centre of the universe. Two thousand years later, human reason having remained stationary, the wish of Cleanthus was realized. Galileo was accused of blasphemy and impiety for having, like Copernicus and following Aristarchus, maintained the same truth; a tribunal condemned his writings, and forced him to a recantation which his conscience denied.The following is the judgement of the historian upon this event:
“Never perhaps has the generous detestation of the public conscience for intolerance shone forth more strongly than around the name of Galileo. The narrative of his misfortunes, exaggerated like a holy legend, has affirmed, while avenging him, the triumph of the truths for which he suffered; the scandal of his condemnation will forever vex in their pride those who would oppose force to reason; and the righteous severity of opinion will preserve its inconvenient remembrance as an eternal reproach thrown in their teeth to confound them.”
The “righteous severity of the judgement” which preserves the inconvenient memory of the sufferings of Galileo, it is well to mention, is that of the scholarly and learned members of Academies whereof the author forms part. It is agreed; yes, intolerance is odious and hateful, the situation of Galileo was particularly horrible. He was forced to go to church and pronounce with a loud voice the abjuration dictated to him.
“I, Galileo, in the seventieth year of my age, on my knees before your Eminences, having before my eyes the holy gospels, which I touch with my own hands, I abjure, I curse, I detest, the error and the heresy of the movement of the earth.”
There is no more atrocious torture than this brutal violence against the conscience of a man. It is the greatest abuse of force and pride when we know that it was the priests of Jesus Christ who perpetrated it.
The theologians of the holy office were not competent to judge the astronomer Galileo, yet they in their ignorance undertook to proscribe an opinion which differed from their own as being erroneous and contrary to the holy Scriptures, which, said the Popes, “were dictated by the mouth of God himself.” In truth what did they know about it? Assuredly it is distressing to observe how long human reason can remain at the same point.
It is then interesting to know whether the lesson taught by the condemnation of Galileo has been properly learned, and if three centuries later “the righteous severity of the judgement against those who would still resist the power of reason” would be able to protect those who labour disinterestedly for the triumph of the truth. Have those who, for the large public, are the authoritative judges of the value of the discoveries of others become less intolerant, or at least more impartial, less prompt to pronounce against opinions which they do not share, and less anxious to deny facts than to test them?
And if the lesson has not been learned, it is not less interesting to ask whether it is “human reason” which must be held responsible; if it might not instead be “pettifogging” ratiocination, the abuse of reasoning warped by passion and too often by personal interest which overcomes private conscience and leads the public astray.
The history of a discussion wherein chemistry and physiology closely united were interested, which agitated the second half of the 19th century, is well adapted to show that human nature has not changed since the time of Cleanthus, and that there always exist people ready to associate themselves together to contradict or insult the unfortunate wretch who has devised some new theory, based upon unsuspected facts, which would compel them to reform their arguments and abandon their prejudices.
This work upon the blood, which I present at last to the learned public, is the crown to a collection of works upon ferments and fermentation, spontaneous generation, albuminoid substances, organization, physiology and general pathology which I have pursued without relaxation since 1854, at the same time with other researches of pure chemistry more or less directly related to them, and, it must be added, in the midst of a thousand difficulties raised up by relentless opponents from all sides, especially whence I least expected them.
To solve some very delicate problems I had to create new methods of research and of physiological, chemical and anatomical analysis. Ever since 1857 these researches have been directed by a precise design to a determined end: the enunciation of a new doctrine regarding organization and life.
It led to the microzymian theory of the living organization, which has led to the discovery of the true nature of blood by that of its third anatomical element, and, at last, to a rational, natural explanation of the phenomenon called its spontaneous coagulation.
But the microzymian theory, which is to biology what the Lavoisierian theory of matter is to chemistry, and which is founded on the discovery of the microzymas, living organisms of an unsuspected category, has been attacked in its principle, by denying the very existence of the microzymas.
Since this was so, if the assertion that the microzymian theory of the living organization gives to biology a base as solid as does the Lavoisierian theory to chemistry be deemed imprudent, well, I choose to commit this imprudence, and to be imprudent to the end, and to struggle against a current of opinion which is the more violent, as will be seen, the more it is artificial.
It was the boldest of those who deny the fact of the existence of the microzymas who wrote:
“Whenever it can be done, it is useful to point out the connection of new facts with earlier facts of the same order. Nothing is more satisfying to the mind than to be able to follow a discovery from its origin to its latest development.”
That is very well and fine, the more so that the author took good care not to follow this wise precept; let us ascend then to the sources.
Two centuries after Galileo, we were still in the Aristotelian hypothesis regarding matter, but reinforced by the alchemical hypothesis of transmutation and the Stahlian one of phlogiston. It was readily conceded that matter could of itself become living matter, animated, such as it is in plants and animals; thus it was that spontaneous generation was still generally accepted.
Charles Bonnet himself said that organization was the most excellent modification of matter; nevertheless that learned naturalist and philosopher attempted to oppose spontaneous generation by imagining in turn the hypothesis of encapsulation and that of pre-existing germs universally diffused, whereof Spallanzani made use to refute the experiments and conclusions of the sponteparist Needham.
On the other hand, to sustain Needham, Buffon invented the hypothesis of organic molecules, not less universally diffused, whose substance, distinct from common matter, called raw matter, helped to explain the growth of plants and animals, as well as spontaneous generation.
Fermentations and ferments were very simply explained. Macquer, in 1772, regarded it as certain that vegetable and animal matters, abstracted from living organisms, under certain conditions of the presence of water and of contact, at least momentarily, with the air and of temperature, become altered of themselves, and ferment, becoming putrid in producing the ferment.
And according to the same principles it was said that water could transmute itself into earth, the earth into a poplar, and that the blood begets itself by the transmutation of flesh into the flowing liquor.
Such in a few words was the condition of science upon these questions before the advent of Lavoisier. In the Lavoisierian theory there is no matter other than that of simple bodies, which are heavy, indestructible by the means at our disposal, and always reappearing the same, not withstanding all the vicissitudes of their various combinations among themselves and the changes of states or allotropic modifications they might undergo. No transmutations and no phlogistication to explain the phenomena.
In this theory, matter is only mineral, simple bodies being essentially mineral. There is no living or animal matter, no matter essentially organic.
That which, long after the time of Lavoisier, chemists have called organic matters are only innumerable combinations in the various proportions which carbon, hydrogen, oxygen, and nitrogen can form, often with other simple bodies at the same time—sulphur, phosphorus, iron, etc, carbon being always present, so that what is called organic matter in modern chemistry is only various combinations of carbon with the simple bodies mentioned.
In fact, Lavoisier, after his demonstration that water did not become transmuted into earth, nor earth into plants, asserted clearly that plants draw their food from the air, as was verified later. He even asserted that animals obtained the materials for their nutrition from plants, thus demonstrating that plants effected the synthesis of the substance without which animals could not exist. Even respiration was only a common phenomenon of oxidation.
The substance of plants and animals being only combinations of carbon with hydrogen and oxygen, with the addition of nitrogen for animals, it is very interesting to recall shortly what Lavoisier thought of the putrefaction of these substances and of fermentation.
Like everybody, he knew that the juice of grapes or apples enters into fermentation of itself to produce wine or cider, and he wrote the following equation:
grape = must = carbonic acid + alcohol
To demonstrate this, he reduced the experiment to the employment of sugar, which he called a vegetable oxide, and of water and a ferment. The following is his account of the experiment:
“To ferment sugar, it must first be dissolved in about four parts of water. But water and sugar, no matter what proportions be employed, will not ferment alone, and equilibrium will persist between the principles (the simple bodies) of this combination if it is not broken by some means.
A little yeast is sufficient to produce this effect and to give the first movement to the fermentation; it then continues of itself to the end. The effects of vinous fermentation reduced themselves to separating the sugar into two portions, to oxygenize the one at the expense of the other to produce carbonic acid of it; to deoxygenize the other in favour of the former to make alcohol of it; so that if it were possible to recombine the alcohol and carbonic acid, the sugar would be reformed.”
It is thus clear that Lavoisier instead of the equation regarding the must might have written thus:
sugar = carbonic acid + alcohol
Lavoisier intended to give elsewhere an account of the effects of yeast and of ferments in general, which he was prevented from doing. But it can be seen from his Treatise upon Elementary Chemistry, published in 1788, that he had established that yeast is a quarternary nitrogenised body, and that that which remained of it at the end of the fermentation contained less nitrogen, and that besides the alcohol, a little acetic acid was formed. Lavoisier also found that after distillation there remained a fixed residue representing about 4% of the sugar. We shall see later the importance of these remarks.
It might thereafter have been anticipated that Lavoisier should explain the phenomena of the putrid fermentation of vegetable and animal substances “as operating by virtue of very complicated affinities” between the constituted principles of these substances (the simple bodies), which in this operation cease to be in equilibrium so as to be constituted into other compounds.
Bichat, who died in 1802 at the age of 31, had been much struck by the results of the labours of Lavoisier. He could not accept a living matter constituted of pure chemical compounds whereof the simple elements are the constituent principles. He imagined, then, that the only living things in a living being are the organs composed of the tissues, of which he distinguished twenty-one as elementary anatomical elements, as the elementary bodies are chemical elements. Such was the first influence of the Lavoisierian theory upon physiological anatomy; it was thus that in 1806 in the third edition of his Philosophie Chimique, Fourcroy said:
“Only the tissue of living plants, only their vegetating organs, can form the matters extracted from them, and no instrument of art can imitate the compositions which are prepared in the organized machines of plants.”
Let us bear in mind that Bichat had been led by the Lavoisierian theory of matter to lay down a new principle of physiology. As Galileo had laid down the metaphysical principle “nothing is but what ought to be”, Dumas drew from the chapter on fermentation of Lavoisier’s treatise the following principle, which is also a necessary one: “nothing is created, nothing is lost.”
We have above rapidly sketched the state of the relations of chemistry and physiology as well as the state of the subject of fermentations at the beginning of the nineteenth century; we will now see what they were at the commencement of the second half of that century, in about 1856.
The chemists, thanks to direct analytical methods which were more and more perfected, had isolated a great number of incomplex compounds, acids, alkaloids, neutral or having diverse functions, from vegetable and animal substances. Those incomplex compounds were more and more exactly specified under the name ofproximate principles of plants and of animals, nitrogenised ternaries and quarternaries.
Among the nitrogenised proximate principles, a number of them were distinguished as soluble or insoluble, and also uncrystallisable, such as the albumin of the white of egg and of the serum of blood, caseum (later called casein) of milk, the fibrin of the blood and that of the muscles, the gelatine of the bones, the gluten of wheat, the albumin of the juices of plants, etc. In time, the similarity of their composition and of certain of their common properties with the albumin of the white of egg led to these matters being formed into the groups of the albuminoid matters.
Lavoisier knew these albuminoid matters only in so far as they were nitrogenised animal matters.
Now after the discovery of gluten, of vegetable albumen, and nitrogenised quarternaries like beer yeast, it was admitted that they were the ferment of vinous fermentation. Then, generalising, it came to be thought that albumin, the albuminoids in general, became or were directly the ferment, while the ternary proximate principles, such as cane sugar, grape sugar, milk sugar, the other sugars, amylaceous matter, inulin, gum, mannite, etc, were called fermentescible matter.
Matters had reached this point when in about 1836, Cagniard de Latour, resuming the study of beer yeast3 and of its multiplication during the fermentation which produces beer, regarded it as organized and living, decomposing the sugar into alcohol and carbonic acid by an effect of its vegetation.
That was a conception as original as that of Bichat. It is not because of his having regarded beer yeast as organised and its multiplication during fermentation as a multiplication by vegetation that the conception of Cagniard de Latour is original; it is because he admitted that the fermentation of the sugar operated by an effect of this vegetation, that is to say, owing to a physiological act.
That was an absolutely new point of view; beer yeast, the only isolated ferment known, ceased to be regarded as a precipitate of albuminoid matter which had become insoluble, and was henceforth looked upon as a living being! Consequently yeast ceased to be regarded as the reagent that Lavoisier had said was able to disturb the equilibrium of the simple bodies which constituted sugar.
Also, soon afterwards, Turpin, the botanist, interpreted the effect of the vegetationof Cagniard by saying that the globule of yeast was a cellule which decomposed sugar in nourishing itself. Dumas went further, and asserted that the ferments, the yeast, behaved as do animals when feeding, and that, for the orderly maintenance of the life of the yeast, there was needed, as for animals, nitrogenised albuminoid matter as well as sugar.
In Germany, Schwann supported the opinion of Cagniard de Latour while broadening the question; he supposed that no animal or vegetable substance altered of itself and that every phenomenon of fermentation presupposed a living ferment. To prove this, he experimented as Spallanzani had done—improving upon his method in order to demonstrate that the infusoria or ferments had their origin in the germs of the air. The experiments of Schwann were confirmed by others.
But the conception of Cagniard de Latour did not prevail, nor especially the interpretation of Turpin and Dumas. It was not denied that infusoria or moulds existed in the mixtures in a state of alteration, but it wasdenied that they were the agents of the fermentation; this would begin of itself and the altered matter was regarded as evidence in favour of either spontaneous generation or the production of these living products by the germs of the air.
The discovery of diastase and synapse, soluble and nitrogenised quarternaries like yeast, was held to legitimize the refusal to consider yeast as acting because it was organized and living.
Now because these substances were reagents of rare power for transforming certain fermentescible matters in aqueous solution, the transformations were called fermentation, and these reagents were called ferments; and it was said that it is not because they are organized and living that the ferments act to effect the phenomena of fermentation.
Then the opponents of the doctrine of Cagniard de Latour and Schwann, with regard to fermentations and the relations of chemistry to physiology, triumphed so completely that opinions reverted to the point maintained in 1788. The principle of Bichat’s doctrine was lost to view; not only was it proposed that vegetable and animal matters altered of themselves under the conditions specified by Macquer, but so too the proximate principles extracted from them, even cane sugar, the aqueous solution whereof Lavoisier had declared to be unalterable.
In short, the old hypothesis of germs of the air, which Schwann had revived, was completely lost to view.
Nothing is better fitted to convince one that the human soul during the second half of the 19th century has remained the same as it was in the times of Galileo and of the inquisition than to reflect upon the sequel of the history I have just sketched out.
I will now describe the fundamental experiment, the results whereof have completely changed the aspect of science with regard to the relations of chemistry and physiology with fermentation, such as they were still imagined to be at the end of the year 1857, after the theory of Cagniard de Latour in relation to yeast had been rejected.
In 1854, it was conceded that cane sugar dissolved in water altered of itself and became transformed into what is called invert sugar, because the solution which deviated the plane of polarisation to the right before the alteration deviated it to the left afterwards. The inverted sugar was also called grape sugar. The phenomenon of this alteration was called inversion.
With reference to other researches I resolved to verify the fact, and in the month of May, 1854, I left to themselves in a closed flask, in the presence of a small volume of air, at ordinary temperature and in a diffused light, some aqueous solutions of pure cane sugar. After several months, I found that the sugar solutions in pure distilled water were partly inverted.
At the beginning of 1855 I published the observation as a verification of the fact, but I mentioned at the same time the presence of a mould in the inverting liquor. It is not an unusual thing to see moulds appear in aqueous solutions of the most diverse substances.
That was why, in the then state of science and given the contradictory assertions regarding the experiments of Schwann, I would not assert anything beyond the fact. I noted merely that in the solutions to which I had added chloride of calcium, or chloride of zinc, the inversion had not taken place and no mould had appeared. To find an explanation of these differences I made various experiments, commencing in 1855 and continuing to the month of December, 1857.
Among these experiments, all accordant with one another, I select two, because, reducing the problem to its simplest expression, they leave no room for doubt concerning the legitimacy of the conclusions I deduced from them.
The first conclusion was that the solution of cane sugar in distilled water remains indefinitely unchanged when, having been boiled, it is preserved in an absolutely full closed vase.
The second was that the same solution, whether boiled or not, left in a closed vessel in the presence of a limited volume of air permits the appearance of colourless moulds, generally myceliennated, and the solution becomes completely inverted in the course of time, while the liquor reddens litmus paper, that is to say, it becomes acid. To prove that the volume of air left in the closed flask has nothing to do with the inversion, it suffices to add beforehand a small quantity of creosote5 or a trace of sublimate of mercury to ensure that the liquid shall not become acid, or mouldy, and that the sugar will remain unchanged.
These two experiments clearly demonstrated to me that the presence of the air was essential for the inversion to take place and for the moulds to be born, and at the same time that the volume of air left present could not operate the inversion.
It was then necessarily the developed moulds which were the agents of the phenomena observed. But myceliennated moulds are true microscopic plants, and consequently organized and living. I proved that they were nitrogenised and that, introduced into creosoted sugar water, they inverted the cane sugar much more rapidly than during their development. Nevertheless these moulds being insoluble, I asked myself: how do they do it? And I supposed that it was by an agent analogous to diastase and also thanks to the acid formed; but I have since demonstrated that it was indeed chiefly by means of a soluble ferment which they contain and which they secrete. And the presence of this soluble ferment, and consequently of an albuminoid matter, explained to me how, being nitrogenised, the moulds, when heated with caustic potash, set free an abundance of ammonia.
But these moulds being nitrogenised could not be born of the cane sugar, which I have proven to be exempt from nitrogen. Besides this sugar there was nothing present but distilled water, the mineral substance of the glass, and no other nitrogen than that of the air left in the closed flask; now (thanks to a little creosote or mercuric chloride) the experiment itself showed that these materials could not unite of themselves, by synthesis, to produce the substance of the moulds. Nothing remained to explain the birth of the organized productions other than the old hypothesis of germs; which allowed me no rest until I had discovered their origin and nature.
While waiting to specify them, I admitted that under the conditions of the experiment “germs brought by the air found in the sugared solution a favourable medium for their development”;6 a development during which the new organism, making use of the materials present, effects the synthesis of the nitrogenised and non-nitrogenised materials of its substance.
Under the conditions of the experiment such as I have reported, where there are no other mineral matters than those of the glass, the crop of organized production is necessarily very small, and the inversion as well as the transformations which follow it are very slow.
The addition of certain salts or of creosote hinders the inversion by preventing the development of the germs, either by rendering the medium sterile or by acting directly upon the former.
But the addition of certain other purely mineral salts, even of arsenious acid, had the effect of increasing the harvest and of singularly hastening the inversion and the other phenomena of fermentation which follow it, for if the reaction is prolonged, the acid of which I have spoken above is found to be acetic acid, with, in certain cases, lactic acid, and alcohol in all cases; but to determine the production of this last the mould must be allowed to act for several years. It was thus that I was able to establish that the study made in 1857 was really a phenomenon of fermentation, for the manifestation of which it had not been necessary to employ albuminoid matter, but which, on the contrary, was produced from these matters.
In its simplicity, the experiment was of the same order for physiological chemistry as had been the observation of Galileo with regard to the lamp, hung by a long cord, which oscillated slowly before the altar of the cathedral of Pisa. From that oscillation it was learned that it always beat the same measure, that the duration of the oscillation is independent of its amplitude, and Huyghens discovered the law of the pendulum’s oscillation by connecting it with the Galilean principle of falling bodies. The consequences which have sprung from the above experiment have not been less fruitful; some day doubtless there will come a genius like that of Huyghens to extend them and increase their fruitfulness; meanwhile the following are some which I have been able to deduce from it, either in 1857 or subsequently while continuing to experiment. The chief and essential facts of the memoir of 1857 are the following.
— Cane sugar, a proximate principle, in watery solution, is naturally unalterable even in contact with a limited volume of air, when the solution has been previously creosoted.
— The solution of cane sugar in contact with a limited volume of air permits the appearance of moulds and the sugar is altered, first of all becoming inverted.
— If the solution has first had creosote added to it, moulds do not appear and the sugar is not altered.
— The fact that moulds develop in sugared water, in contact with a small limited quantity of air, forms the verification of the hypothesis of atmospheric germs; in no other way can that fact be explained.
— Developed moulds invert the cane sugar, even when the solution has first been creosoted, i.e. the creosote which hinders the moulds from being born does not prevent them, when born, from acting. Moulds, being insoluble by reason of their being organized, effect the inversion by means of an agent analogous to diastase; that is to say, by means of a soluble ferment.
— The totality of the phenomena of the non-spontaneous alteration of cane sugar and the production of an acid and of alcohol prove it to be a fermentation both of moulds and of ferments.
These facts, studied more attentively, showed clearly, contrary to what had before been believed, that albuminoid matter was not necessary for the birth of these ferments; and also that the soluble ferments were not the products of the alteration of some albuminoid matter, since the mould produced at once the albuminoid matter and the soluble ferment by virtue of its physiological functions of development and nutrition.
Thus it resulted that the soluble ferment was allied to the insoluble by the relation of product to producer; the soluble ferment being unable to exist without the figured ferment, which is necessarily insoluble.
Further, as the soluble ferment and the albuminoid matter, being nitrogenised, could only be formed by obtaining the nitrogen from the limited volume of air left in the flasks, it was at the same time demonstrated that the free nitrogen of the air could help directly in the synthesis of the nitrogenised substance of plants. Up to that time this had been a disputed question.
Thenceforward it became evident that since the synthesis of the materials of the substance of moulds, of ferments, is necessarily produced by intussusception within the organism of these moulds, it must necessarily be that all the products of fermentation are produced there and that they are secreted therein as was secreted the soluble ferment which inverted the cane sugar.
Hence I became assured that that which is called fermentation is, in reality, the phenomenon of nutrition; i.e. the assimilation, dissimulation, and excretion of the products dissimulated.
Without doubt, these views were in conformity with the conceptions of Cagniard de Latour, even to those of Schwann and to the more precise view of Turpin and especially of Dumas; but in complete disagreement with those of their opponents, Liebig and his followers, some of whom denied that yeast was living, and held it to be nitrogenous matter in a state of decomposition, and others that it acted in so far as it was nourished, by an action of extalyic contact, an occult cause, and that it effected the decomposition of sugar in the same manner as did platinum that of oxygenated water.
We must then demonstrate that that which was true of the moulds was so in the same sense as in the case of beer yeast and of the ferment of the lees of wine; that is to say, that the cellules of these ferments invert cane sugar under the same conditions, in spite of the creosote, and before any other phenomenon of transformation is produced. It is found, in effect, that the yeast contains the soluble ferment which inverts, as the mould also contains it.
Nevertheless, the opponents of the conception of Cagniard de Latour and Schwann could always object that if the creosote prevents the cane sugar from being altered, it would not be the same in the case of a mixture containing albuminoid matter, and that consequently, if in the mixture of sugared water and beer yeast, the cane sugar was inverted, it was because beer yeast, an albuminoid substance, continued to be altered in spite of the creosote.
I replied by demonstrating that under the same conditions as the cane sugar all the true proximate principles, including soluble and insoluble albuminoids, even the most complex mixtures of proximate principles, remained unchanged, nothing organized appearing in them—provided that in the cases wherein cane sugar is present, the inverting soluble ferment does not exist among these proximate principles, because creosote does not prevent double ferments from reacting.
Two contemporary experiments of that fact greatly impressed me. The first relates to milk. Everybody except Dumas regarded milk as an emulsion, as a pure mixture of proximate principles. Now, it is known that, like blood, it alters and clots after it is drawn, as Macquer said in the last century (the 18th).
This furnished an opportunity to verify the fact of the unchangeableness of mixtures of proximate principles when creosoted.
The milk of a cow was then creosoted while being drawn, by receiving it into vessels washed with boiling creosoted water divided into three portions; one of which was left with a limited volume of air present; a second was left without any, and in the third the air was expelled by a current of carbonic acid gas. To my very great surprise, the milk altered, became sour and clotted, almost as quickly as if no creosote had been added. And lastly, which surprised me most of all, shortly after the coagulation was completed, there was a crowd of bacteria in every part of the clot.
The second experiment relates to the chalk which chemists employed, as calcic carbonate, in their experiments even upon fermentation, and which, like them, I employed to preserve the neutrality of the media.
One day, some starch made of potato fecula had some chalk added to it to prevent it turning sour and was left in an oven at 4o to 45oC (104o to 113oF). I expected to find the starch with the same consistency as before; on the contrary, it was liquefied. “The germs of the air,” I said.
I repeated the experiment, creosoting the boiling starch and added some of the same chalk; again liquefication! Much astonished, I repeated the experiment, replacing the chalk with pure artificial calcic carbonate; this time the creosoted starch was not liquefied, and I preserved it in this state for ten years.
These two experiments, in their simplicity, were of the same order, equally fundamental as that of the inversion of sugar by moulds, but they embarrassed me much more.
It was not until after other researches and after having varied and controlled them that I placed them before the learned societies of Montpellier (1863) and informed Dumas of them in a letter which he thought fit to publish,8 in which I stated that some of the calcareous earths and milk contained living beings already developed.
And here are three other experiments, not less fundamental, which verify the first three:
1 – I had ascertained that in the fermentation of cane sugar by moulds born of atmospheric germs, in a watery solution of sugar, acetic acid is produced; why is it not also produced in fermentation by beer yeast? And I shall prove that there is, in fact, produced at the same time only a very small quantity of acids homologous to acetic acid.
2 – Beer yeast inverting cane sugar as do moulds, I tried to isolate from the yeast the soluble ferment it produces, as one can readily obtain as much beer yeast as may be required. I will say here how I proceeded to isolate it directly. Brewery yeast, pure, washed and drained, was treated with powdered cane sugar in suitable quantity. The mixture of the two bodies became liquefied and the sugar was entirely dissolved. The product of the liquefaction was thrown upon a filter. If the operation is performed on a sufficiently large quantity, there results the flowing off of an abundant limpid liquid before any indication of fermentation is manifested. The filtered liquid, being treated with alcohol, furnishes (as does an infusion of sprouted barley to precipitate its diastase) a rather considerable white precipitate, whereof the part soluble in water is the required soluble ferment. There could be no further doubt; this soluble ferment forms part of the very substance of the content of the cellule of the yeast. I gave it the name first of zymas, and later that of zythozymas.
3 – The cellule of yeast, being a living organism, ought, being insoluble, to possess a vital resistance and should permit only such things to issue from its being as were disassimilated in it. Now, in effect, pure yeast, subjected to a methodical washing with distilled water, yields to it at first scarcely anything, only a trace of zythozymas and phosphoric acid. But there comes a time when it yields enormously, then less and less, until it has lost nearly 92% of its substance, preserving its form with its tegument distended with water. The observation suggested a comparison with the famous experiment of Chossat upon starving dogs. To compel the yeast to dwell in pure water would be to deprive it of nourishment; to submit it to a regimen of starvation would force it to devour itself. Pure yeast, steeped in creosoted distilled water, absolutely protected from air, disengages pure carbonic acid for a long time, producing alcohol, acetic acid, etc, and at the same time other compounds which it does not make when nourished upon sugar. It exhausts itself thus enormously, remains whole a long time, its tegument preserving its form and, having eliminated its content almost wholly, inverts cane sugar to the end. I thus demonstrated that notwithstanding the creosote, the yeast alters of itself, as does the milk.
The spontaneous alteration of milk and that of yeast seemed to me indisputable proof that neither milk nor yeast was a mixture of proximate principles, but that both of them contain, inherently, the living organized agent which is the cause of their spontaneous alteration, or that consequently, if the chalk liquefies fecula starch, it is because it contains that which can produce the necessary soluble ferment.
It was the experiment of starving the yeast which enabled me to complete the demonstration that the phenomenon called the fermentation of cane sugar by yeast was the digestion of the sugar by the zymas, the absorption of the digested (invert) sugar by the cellule, the decomposition of this sugar in the cellule being the result of the complex phenomenon of assimilation, followed necessarily by disassimilation and of elimination. The products eliminated were carbonic acid, alcohol, acetic acid, etc, the same as with man the products of disassimilation—urea, etc.—come from man and reunite in part in urine.
While I was thus experimenting to develop the consequences of the memoir of 1857 and discovered the zythozymas in the yeast, I also discovered anthozymas in flowers, morozymas in the white mulberry, and the nefrozymas of the kidneys in the urine as a product of the function of the kidneys, in order to demonstrate that as the moulds form and secrete their soluble ferment, plants and animals form theirs in their organs, and I shall demonstrate besides that the leucocytes of pus even produce a zymas in the pus.
The phenomenon called fermentation is then the phenomenon of nutrition, which is being accomplished in the ferment, in the cellule of the yeast, in the same manner as the phenomenon of nutrition is accomplished in the animal, and following the same mechanism by the same means. This was the fundamental idea of my memoir Upon Fermentations by Organized Ferments which dates from 1864.
I will revert later, with details, to this work, which is fundamental. I mention it now only as a verification of the conception of Dumas of which mention has before been made; it was in that work that for the first time the word zymas is employed to designate the soluble ferment which yeast contains performed, distinguishing the soluble ferments as agents of a different order from the figured ferments and effecting transformations also of a different order.
For the history one should read, in the Jahresbericht of Heinrich Will for 1864, how this was regarded as new in Germany and was favourably appreciated.
It is difficult, however, to realize the resistance which was offered from many sources to the demonstration that the phenomenon of fermentation is a phenomenon of nutrition accomplishing itself in the ferment. It was simply because although Virchow had held that the cellules were living in a living organism, the conception of Bichat was more and more regarded as unacceptable and the hypothesis of the cellularists as unfounded.
Alfred Estor, who was interested in my researches, in giving an account of them in 1865, expressed himself as follows:
Seven years had passed since the publication of the memoir upon the inversion of cane sugar by moulds, when Estor delivered this judgement and when I wrote to Dumas the letter upon living agents which, in the milk, effect its spontaneous alteration and which, in the chalk, effect the liquefaction and fermentation of fecula starch. The year following I first named the microzymas in the Comptes Rendus of the Academy of Sciences to designate the ferments of the chalk.
It has been known since the time of Leuwenhoeck (17th century) that human saliva contains a great number of microscopic organisms long since recognised as vibrioniens, but which in a cleanly kept mouth I have found to be chiefly microzymas.
I supposed that, even as the “little bodies” inverted cane sugar in the experiments of 1857, these microzymas might be those which produced the salivary diastase of Miathe in the saliva. I interested Estor and Camille Saintpiere in this question, and in 1867 we addressed a note to the Academy, having this title: On the Role of the Microscopic Organisms of the Mouth in Digestion in General, and Particularly in the Formation of the Salivary Diastase. The note was sent for examination to a commission composed of Louget and Robin, who made no report, and the note was mentioned in the Compte Rendu in the following terms:
We demonstrated two facts, equally essential; that the buccal microzymas of man liquefy and saccharify the starch of fecula with rare energy; that the parotidian saliva of the dog or horse can also liquefy starch, but does not saccharify it, while such as has stayed upon the buccal organisms soon becomes as saccharifying as human saliva.
The short note inserted by the commissioners shows that they had no idea of a zymas produced as a function of a cellule, of a vibrionien, or of a microzyma, nor even of an organ. Here is an indisputable proof thereof: the pancreas was known and it was called an intestinal salivary gland.
Now Bernard and Berthelot, studying the pancreatic juice and isolating from it the soluble substance calledpancreatin, never thought for a moment to compare it to the salivary diastase, although it possessed, to the same degree, the power of saccharifying the starch of fecula; that is, Bernard, contrary to the opinion of Longet and of Mialhe, held that salivary diastase, according to the ideas of Liebig, was an animal matter in a condition of alteration.
The microzymas being discovered, the general demonstration was made that the soluble ferments were substances produced by a living organism, mould, yeast, geological microzyma, diverse flowers, a fruit, the kidneys, and the buccal microzymas. But these were only the preliminary researches, whereof the totality have, since 1867, enabled the microzymian theory of the living organism to be formulated.
After our joint experiment upon the buccal microzymas, I showed Estor an experiment in which a piece of muscle placed in fecula starch, after having liquefied it and commenced to make it ferment, caused bacteria to appear in it as they appeared in soured and clotted milk. He then became my collaborator in proving that that which was true of milk and meat was also true for all the parts of an animal. There has resulted from this, thanks to other collaborations and other researches subsequent to 1870, the microzymian theory of the living organism, the construction whereof is completed by the present work.
The new theory rests upon a collection of fundamental and new facts which may by ranged under the following heads:
What does this similitude of form and of function mean? What was there in common between a microzyma proceeding from a germ of the air, a microzyma of the chalk, a microzyma of the milk, and those of natural organic matters?
Ever since 1870 all my efforts have been directed to its discovery. My joint researches with Estor, later those of Baltus, upon the source of pus; those of J. Béchamp upon the microzymas of the same animal at its various ages and my own, especially those upon milk, eggs and the blood, have led me to consider the microzymas not only as being living ferments and producers of zymases, like the moulds born in sugared water, but as belonging to a category of unsuspected living beings without analogy, whose origin is the same.
In fact, first, all these researches showed me these microzymas functioning like anatomical elements endowed with physiological and chemical activity in all the organs and humours of living organisms in a perfect state of health, preserved there morphologically alike and functionally different, ab ovo et semine, in all the tissues and cellules of the diverse anatomical systems, down to the anatomical element which I have called microzymian molecular granulation. And especially, they showed me that the cellule is not the simple vital unit that Virchow believed, because the cellule itself has microzymas as anatomical elements.
Secondly, the experiment showed me that in parts subtracted from the living animal, the microzymas, being no longer in their normal conditions of existence, produced therein chemical alterations, called fermentations, which inevitably led to tissue disorganizations, to the destruction of the cellules and to the setting free of their microzymas, which then, changing in form and function, could become vibrioniens by evolution, which they did whenever the conditions for this evolution were realized.
And, thirdly, I established that the vibrios, the bacteria which the anatomical microzymian elements had become, destroyed themselves, and that, with the aid of the oxygen of the air, under the conditions which I had realized, they were at last reduced to microzymas while the matters of the alteration, being oxidised, were transformed into water, carbonic acid, nitrogen, etc, i.e. they were restored to the mineral condition, so that of the natural organic matters and of their tissues and cellules there remained only the microzymas.
These microzymas, proceeding from the bacteria which the anatomical element microzymas had become, were identical, morphologically and functionally, with those of chalk, calcareous rocks, alluviums, water, arable or cultivated earths, or the dusts of the streets and the air. From these experiments, I argued that the microzymas of the chalk, etc, were the microzymas of the bacteria which the anatomical element microzymas of the living beings of the geological epochs had become!
We then have to consider:
1 – The microzymas in their function as anatomical elements in the living and healthy organism; there they are the physiological and chemical agents of the transformations which take place during the process of nutrition.
2 – Microzymas in natural organic matter abstracted from the living animal, or in the cadaver; there they are the agents of the changes which are ascertained to take place there, whether or not they undergo the vibrionien evolution—changes which lead to the destruction of the tissues and the cellules.
3 – The microzymas of the bacteria which result from this evolution, which are essentially ferments productive of lactic acid, acetic acid, alcohol, etc, with sugar and fecula starch; these microzymas are also producers of zymases and are capable of again undergoing vibrionien evolution.
The microzymas being the anatomical elements of the organized being from its first lineaments in the ovule which will become the egg, I am able to assert that the microzyma is at the commencement of all organization. And the microzymas of the destroyed bacteria being also living, it follows that these microzymas are the living end of all organization. The microzymas are surely then living beings of a special category without analogue.
But that is not all. Estor and I demonstrated that in a condition of disease, the microzymas which have become morbid determine in the organism special changes, dependent upon the nature of the anatomical system, which lead alike to the disorganization of the tissues, to the destruction of the cellules and to their vibrionien evolution during life, so that the microzymas, living agents of all organization, are also the agents of disease and death under the influences which nosologists specify.
Finally, they are the agents of total destruction when the oxygen of the air intervenes. Like the indestructible atom or element in the Lavoisierian theory of matter, the microzymas, too, are physiologically imperishable.
From the experimental fact that the microzymas of the chalk and dusts of the air are only microzymas from bacteria which proceeded from the vibrionien evolution of the anatomical element microzymas, it follows that that which I have called germs in my verification of the old hypothesis of germs of the air are not pre-existent in the air, in the earth and in the waters, but are the living remains of organisms which have disappeared and been destroyed.
The facts of the microzymian theory have legitimatized the genial conception of Bichat; that the only thing living in an organism is what he regarded as elementary tissues. Later, among cellularists, Virchow, following Gaudichaut, held that the cellule was the simple anatomical element from which proceeded the whole of a living being; but it is in vain that he contended that it is the vital unit, living per se, because every cellule, even that of beer yeast, is transitory, destroying itself spontaneously.
It is the microzyma which enables us to specify precisely wherein a tissue, a cellule is living; living per se—that is to say, autonomically, it is in truth the simple vital unit.
But the conception had none the less as a consequence the assertion that, in disease, it is the elementary tissues or the cellules which are affected.
Tissue and cellular physiology now being established in accordance with the prevision of Estor, it should result from this that tissue and cellular pathology are in reality microzymian pathology.
In disease, the cellules have been seen to change, to be altered and destroyed, and these facts have been noted. But if the cellule were the vital unit living per se, it would know neither destruction nor death, but only change. If then the cellule can be destroyed and die, while the microzyma can only change, it is because the microzyma is really living per se, and physiologically imperishable even in its own evolutions, for, physiologically, nothing is the prey of death; on the contrary, experience daily proves that everything is the prey of life, that is to say, of what can be nourished and can consume.
From the beginning of our researches, Estor and I have established the presence of microzymas in the vaccine matter, in syphilitic pus as in ordinary pus, and I have shown in pus (even laudable) the presence of a zymas. In diseases there is, then, a morbid evolution of some anatomical element which corresponds to a vicious functioning and to vibrionien evolution.
It is thus that in anthrax the morbid microzymas of the blood become the bacteria of Davaine, and the blood globules experience such remarkable changes. But even as the microzymas may become morbid, they may cease to be so. For instance, there is a leading observation of Davaine upon the non-transmissibility of anthrax even by inoculation; if the animal is in process of putrefaction, its blood can no longer communicate anthrax.
From this observation of Davaine, I draw the conclusion that normal air never contains morbid microzymas, or what used to be called germs of diseases and are now called microbes; maintaining, in accord with the old medical aphorism that diseases are born of us and in us, that no one has ever been able to communicate a characteristic disease of the nosological class (anthrax, smallpox, typhoid fever, cholera, plague, tuberculosis, hydrophobia, syphilis, etc.) by taking the germ in the air, but necessarily from a patient, at some particular moment. And within the limit of my own studies upon the silkworms I distinguished with care the parasitic diseases whereof the agent came from outside, such as the muscardine and the pebine, from constitutional diseases, such as the flacherie, which is microzymian.
I give in the postscript of this work the communication which I made to the Academy of Medicine on the 3rd May, 1870, upon Les Microzymas, la Pathologie et la Therapeutique. It will help to establish the date, and will show that the theory was then nearly complete. It was not inserted in the Bulletin of the Academy, but an able physician, who gave an account of it in the Union Médicale of Paris, remarked that had it come from Germany it would have been received with acclamation. But there was not at that time any question about the medical doctrines of Pasteur and I did not then have to defend the microzymas against the denials of that savant; it was otherwise some years later.
The foregoing exposition shows clearly the connection of the new facts of the microzymian theory with certain earlier facts of the same kind, ascending to Bichat and Macquer, who, in agreement with the science anterior to Lavoisier, recognized the spontaneous alterability of natural organic matters; and at length Spallanzani, who, to explain certain apparitions of organized beings ascribed to spontaneous generation, invoked the germs of the air. It has enabled me further to follow the connection of the successive discoveries of special facts which, since 1854, the commencement of these researches, have resulted in the discovery of the microzymas and to the demonstration that the blood is a flowing tissue.
It is important to remark that the microzymian theory is in no way the product of a system or of a conceptiona priori, nor is it the consequence of a desire to demonstrate that the conception of Bichat and the cellular theory are conformable to nature. In fact, it has had for a point of departure the solution of a problem of pure chemistry and the necessity of discovering the role of the moulds in the inversion of a solution of cane sugar exposed to the air. Then, from induction to induction, applying unceasingly the method of Lavoisier, and from the attentive study of the properties of the lowest organism, I ascended to the highest summits of physiological chemistry and of pathology to discover wherein vital organization consists.
But so fertile is this theory founded upon the nature of things, and which has as its base no gratuitous hypothesis, that after it had led me to discover the source of the zymases, the physiological theory of fermentations, the nature of what were called the germs of the air, it enabled me to understand what was true in the ideas of Bichat, Dumas, and in the cellular pathology of Virchow and what profound truths there are in the aphorisms of the old physicians.
The microzymian theory of the living organism is true because it agrees at the same time with these conceptions and with the three aphorisms which I have chosen as the epigraph to this first part of my preface.