The _bacillus anthracis_ was first seen more than fifty years ago: "Anthrax has the distinction of being the first infectious disease the bacterial nature of which was definitely proven."[16] Pollender in 1844, Roger and Davaine in 1850, noted the _petits bâtonnets_ in the blood of sheep dead of the disease, and thought they were some sort of microscopic blood-crystals: it was not till 1863, after Pasteur's study of lactic-acid fermentation, that Davaine realised they were living organisms. Afterward, Koch succeeded in making cultures of them, and reproduced the disease by inoculating animals with these cultures; yet it was said, so late as 1876, that the _bacillus anthracis_ was not the cause of anthrax, but only the sign of it: "Along with the bacilli, there are blood-cells and blood-plasma, and these contain the true amorphous virus of anthrax." Then came Pasteur's work, and reached its end in the experiments at Chartres, and the famous test-inoculations (1881) at Pouilly-le-Fort. [16] See Dr. Flexner's account of the disease, in volume xix. of Stedman's _Twentieth Century Practice_. In the _Agenda du Chimiste_ (1896) M. Roux gives the following account of this work, which he watched from first to last:-- "Vaccination against _charbon_ has now been put to the test of practice for fourteen years. Wherever it is adopted, there the losses from _charbon_ have become insignificant. It was followed by vaccination against swine-measles, _rouget des porcs_, the special study of our poor friend Thuillier. But the immediate result of Pasteur's vaccinations is their least merit: they have given men absolute faith in a science that could show such good works, they have started a movement that is irresistible; above all, they have set going the whole study of immunity, which is bringing us at last to a right way of treating infective diseases.