The life of Pasteur

by René Vallery-Radot

“After carefully examining the blood of the three animals after their death, I was unable,” said M. Feltz, “to detect the least difference; not only the blood, but the internal organs, and notably the spleen, were affected in the same manner.”... “It is a certainty to my mind,” he wrote to Pasteur, “that the contaminating agent has been the same in the three cases, and that it was the bacteridium of what you call anthrax.”

There was therefore no such thing as a leptothrix puerperalis. And it was at a distance, without having seen the patient, that Pasteur said: “That woman died of charbon.” With an honourable straightforwardness, M. Feltz wrote to the Académie des Sciences relating the facts.

“It is doubly regrettable,” he concluded, “that I should not have known charbon already last year, for, on the one hand, I might have diagnosed the redoubtable complication presented by the case, and, on the other hand, sought for the mode of contamination, which at present escapes me almost completely.” All he had been able to find was that the woman, a charwoman, lived in a little room near a stable belonging to a horse dealer. Many animals came there; the stable might have contained diseased ones; M. Feltz had been unable to ascertain the fact. “I must end,” he added, “with thanks to M. Pasteur for the great kindness he has shown me during my intercourse with him. Thanks to him, I was able to convince myself of the identity between the bacillus anthracis and the bacteridium found in the blood of a woman who presented all the symptoms of grave puerperal fever.”

At the time when that convincing episode was taking place, other experiments equally precise were being undertaken concerning splenic fever. The question was to discover whether it would be possible to find germs of charbon in the earth of the fields which had been contaminated purposely, fourteen months before, by pouring culture liquids over it. It seemed beyond all probability that those germs might be withdrawn and isolated from the innumerable other microbes contained in the soil. It was done, however; 500 grammes of earth were mixed with water, and infinitesimal particles of it isolated. The spore of the bacillus anthracis resists a temperature of 80° C. or 90° C., which would kill any other microbe; those particles of earth were accordingly raised to that degree of heat and then injected into some guinea-pigs, several of which died of splenic fever. It was therefore evident that flocks were exposed to infection merely by grazing over certain fields in that land of the Beauce. For it was sufficient that some infected blood should have remained on the ground, for germs of bacteridia to be found there, perhaps years later. How often was such blood spilt as a dead animal was being taken to the knacker’s yard or buried on the spot! Millions of bacteridia, thus scattered on and below the surface of the soil, produced their spores, seeds of death ready to germinate.

And yet negative facts were being opposed to these positive facts, and the theory of spontaneity invoked! “It is with deep sorrow,” said Pasteur at the Académie de Médecine on November 11, 1873, “that I so frequently find myself obliged to answer thoughtless contradiction; it also grieves me much to see that the medical Press speaks of these discussions in apparent ignorance of the true principles of experimental method....

“That aimlessness of criticism seems explicable to me, however, by this circumstance—that Medicine and Surgery are, I think, going through a crisis, a transition. There are two opposite currents, that of the old and that of the new-born doctrine; the first, still followed by innumerable partisans, rests on the belief in the spontaneity of transmissible diseases; the second is the theory of germs, of the living contagium with all its legitimate consequences....”

The better to point out that difference between epochs, Pasteur respectfully advised M. Bouillaud, who was taking part in the discussion, to read over Littré’s Medicine and Physicians, and to compare with present ideas the chapter on epidemics written in 1836, four years after the cholera which had spread terror over Paris and over France. “Poisons and venoms die out on the spot after working the evil which is special to them,” wrote Littré, “and are not reproduced in the body of the victim, but virus and miasmata are reproduced and propagated. Nothing is more obscure to physiologists than those mysterious combinations of organic elements; but there lies the dark room of sickness and of death which we must try to open.” “Among epidemic diseases,” said Littré in another passage equally noted by Pasteur, “some occupy the world and decimate nearly all parts of it, others are limited to more or less wide areas. The origin of the latter may be sought either in local circumstances of dampness, of marshy ground, of decomposing animal or vegetable matter, or in the changes which take place in men’s mode of life.”

“If I had to defend the novelty of the ideas introduced into medicine by my labours of the last twenty years,” wrote Pasteur from Arbois in September, 1879, “I should invoke the significant spirit of Littré’s words. Such was then the state of Science in 1836, and those ideas on the etiology of great epidemics were those of one of the most advanced and penetrating minds of the time. I would observe, contrarily to Littré’s opinion, that nothing proves the spontaneity of great epidemics! As we have lately seen the phylloxera, imported from America, invade Europe, so it might be that the causes of great pests were originated, unknowingly to stricken countries, in other countries which had had fortuitous contact with the latter. Imagine a microscopic being, inhabiting some part of Africa and existing on plants, on animals, or even on men, and capable of communicating a disease to the white race; if brought to Europe by some fortuitous circumstance, it may become the occasion of an epidemic....”

And, writing later, about the same passage: “Nowadays, if an article had to be written on the same subject, it would certainly be the idea of living ferments and microscopic beings and germs which would be mentioned and discussed as a cause. That is the great progress,” added Pasteur with legitimate pride, “in which my labours have had so large a share. But it is characteristic of Science and Progress that they go on opening new fields to our vision; the scientist, who is exploring the unknown, resembles the traveller who perceives further and higher summits as he reaches greater altitudes. In these days, more infectious diseases, more microscopic beings appear to the mind as things to be discovered, the discovery of which will render a wonderful account of pathological conditions and of their means of action and propagation, of self-multiplication within and destruction of the organism. The point of view is very different from Littré’s!!”

On his return to Paris, Pasteur, his mind overflowing with ideas, had felt himself impelled to speak again, to fight once more the fallacious theory of the spontaneity of transmissible diseases. He foresaw the triumph of the germ theory arising from the ruin of the old doctrines—at the price, it is true, of many efforts, many struggles, but those were of little consequence to him.