“Our researches”—thus ran the report to the Academy—“may be summed up in the following propositions—
“I. The swine fever, or rouget disease, is produced by a special microbe, easy to cultivate outside the animal’s body. It is so tiny that it often escapes the most attentive search. It resembles the microbe of chicken cholera more than any other; its shape is also that of a figure 8, but finer and less visible than that of the cholera. It differs essentially from the latter by its physiological properties; it kills rabbits and sheep, but has no effect on hens.
“II. If inoculated in a state of purity into pigs, in almost inappreciable doses, it speedily brings the fever and death, with all the characteristics usual in spontaneous cases. It is most deadly to the white, so-called improved, race, that which is most sought after by pork-breeders.
“III. Dr. Klein published in London (1878) an extensive work on swine fever which he calls Pneumo-enteritis of Swine; but that author is entirely mistaken as to the nature of the parasite. He has described as the microbe of the rouget a bacillus with spores, more voluminous even than the bacteridium of splenic fever. Dr. Klein’s microbe is very different from the true microbe of swine fever, and has, besides, no relation to the etiology of that disease.
“IV. After having satisfied ourselves by direct tests that the malady does not recur, we have succeeded in inoculating in a benignant form, after which the animal has proved refractory to the mortal disease.
“V. Though we consider that further control experiments are necessary, we have already great confidence in this, that, dating from next spring, vaccination by the virulent microbe of swine fever, attenuated, will become the salvation of pigsties.”
Pasteur ended thus his letter of December 3: “We shall start to-morrow, Monday. Adrien Loir and I shall sleep at Lyons. Thuillier will go straight to Paris, to take care of ten little pigs which we have bought, and which he will take with him. In this way they will not be kept waiting at stations. Pigs, young and old, are very sensitive to cold; they will be wrapped up in straw. They are very young and quite charming; one cannot help getting fond of them.”
The next day Pasteur wrote to his son: “Everything has gone off well, and we much hope, Thuillier and I, that preventive vaccination of this evil can be established in a practical fashion. It would be a great boon in pork-breeding countries, where terrible ravages are made by the rouget (so called because the animals die covered with red or purple blotches, already developed during the fever which precedes death). In the United States, over a million swine died of this disease in 1879; it rages in England and in Germany. This year, it has desolated the Côtes-du-Nord, the Poitou, and the departments of the Rhone Valley. I sent to M. Dumas yesterday a résumé in a few lines of our results, to be read at to-day’s meeting.”
Pasteur, once more in Paris, returned eagerly to his studies on divers virus and on hydrophobia. If he was told that he over-worked himself, he replied: “It would seem to me that I was committing a theft if I were to let one day go by without doing some work.” But he was again disturbed in the work he enjoyed by the contradictions of his opponents.
Koch’s reply arrived soon after the Bollène episode. The German scientist had modified his views to a certain extent; instead of denying the attenuation of virus as in 1881, he now proclaimed it as a discovery of the first order. But he did not believe much, he said, in the practical results of the vaccination of charbon.