Louis Pasteur (1822-1895) in 1886.

On 5 November 1860, Pasteur communicates a relation of his trip to Chamonix to the Academie des sciences.  He writes notably:

“If one compares all the notes that I have taken up to now, it can be affirmed, it seems to me, that the dusts in suspension in the air are the exclusive origin, the primary and necessary condition, for the life within the infusions.”

And in a little sentence that no-one notices at this epoch:

“What would be most desirable, would be to take these studies as far as possible to prepare the way for serious research on the origin of diverse illnesses.”

So, the role of these organized, microscopic beings already appeared to him not only as agents of fermentation, but also as factors of disorganization and putrefaction.  Underneath Pasteur the Chemist, Pasteur the Biologist was already sprouting.  The liquids he had been using up until then had been brought to the boil.  Isn’t there a new decisive experiment to perform?  For example, expose fresh, strongly putrescible liquids, like blood?  Claude Bernard, the great physiologist, wanting to associate himself with his colleague’s experiments, took blood from a dog.  This blood was put in a glass balloon, and this balloon was locked inside a sterilizer constantly heated to thirty degrees, from 3 March until 20 April 1863, the day when Pasteur placed it on the Academie des science‘s desk:  the blood had not suffered putrefaction of any sort.

“The conclusions to which I have been led by the first part of my experiments are therefore applicable in all cases to organic substances…”

All that is fermentation, degradation, transformation of “living” matter exercises a veritable fascination on the scholar:  he suspects the intervention of microscopic beings, of invisible agents, exterior to this matter, and which work silently on its metamorphosis.  It must therefore be possible to control their development.  What is the mechanism of the grape’s transformation into alcohol?  Perhaps the action of “infinitely small beings”?  The 1863 holidays arrive, along with the period of the vendanges in his Arbois homeland.  Pasteur will take advantage of this to do some studying.

While he is hunting yeast in bunches of grapes under his microscope, the heterogenists are refurbishing their retorts.  Three years after Pasteur the Chemist’s stay in the Alps, Pouchet the Naturalist, accompanied by Joly, Doctor in Medicine, and by his pupil Musset, climb in the Pyrenees to an altitude of 3,000 metres with glass balloons similar to those of his adversary.  Leaving from Bagnieres-de Luchon,

“better mounted on the principles of Physiology than on our little horses”,

as Musset would jokingly say, the three Scientists go through the Port of Venasque then climb on foot with guides as far as the base of one of the biggest glaciers of the Maladetta.  The return is perillous;  they almost lose Joly in an abyss.  All three return, forgetting the dangers faced, proud of having gone a thousand metres higher than Pasteur, to note with great joy that the contents of all of their balloons are troubled and filled with micro-organisms.  Irrefutable proof for them that, the pure air of the Maladetta not being able to contribute any germs, these organized beings were therefore born spontaneously inside the bottle.  Sure of their facts, Joly and Musset ask the Academie in November 1863, to name a Commission so that their experiments and those of Pasteur be repeated before this scholarly assembly.

The Chemist takes up the gauntelet and prays the Academie to name the Commission as asked by his adversaries, as soon as possible.  Pouchet and his friends tergiverse;  the Commission is therefore postponed to June 1864.  Two months before this meeting, on 7 April, Pasteur holds a conference in the Sorbonne’s great amphitheatre.  To win public opinion to his theories, he has prepared this conference like a show.  On this day, the Sorbonne is beseiged by the public, the seats are full, there are even people in the corridors and passage-ways.

“This was a tough moment for crinolines”,

the journalist Victor Meunier would write.  Amongst the Professors and students, George Sand, Alexandre Dumas Senior, Minister Victor Duruy and Princess Mathilde are recognized.  Pasteur appears onstage:

“Turn out all the lights!  Make it black around us, make everything dark and let us light ourselves only with these little bodies that dance in the air, then we shall see, like in the evening we see stars.  Turn on the projectors!  You can see, Ladies and Gentlemen, dust moving around in the ray of light.  Shine the projectors onto the straw, please!”

The scholar’s serious face is filled with concentrated energy and meditative power.  As a man penetrated with the high mission of teaching and one who is responsible for minds, he begins in a firm, deep voice:

“Very great problems perturb us today and keep all minds in alert:  unity or multiplicity of the human races, creation of Man a thousand years ago or a thousand centuries ago, fixity of species, or slow, gradual transformation of these species, matter reputed eternal, outside it the Void, the idea of God useless, these are some of the questions delivered up today to men’s arguments.  I come to a question accessible to experimentation, and which has been the object of long and severe studies:  can beings come into the world without having been preceded by living beings of the same species?  Without parents that resemble them?  To resume, can matter organize itself on its own?”

While speaking, Pasteur slowly goes towards the covered earthenware tiled table which shines under the projectors, in the centre of the stage.  On it, only a few glass bottles with a curious shape, experimental balloons filled with liquid, a microscope, a stove and a gas burner.  An assistant, a secondary actor, passes the accessories to the orator.  For a second, you think that you are seeing the scholar in his own laboratory.

“I place a portion of this infusion of organic matter in a vase with a long neck, such as this one.  I boil the liquid, and then I let it cool.  After a few days, there will be some mould and infusionary animalcules which have developed in this liquid.  By boiling it, I have destroyed the germs that might have existed in the liquid and on the surface of the sides of the vase.  But as this infusion has been put back in contact with the air, it alters like all infusions.”


To be continued.