FOR THE FARMERS

New Zealand Times, Volume XLIX, Issue 11252, 3 July 1922, Page 3

FOR THE FARMERS

ANTHRAX INVESTIGATION FROM "PASTEUR AND HIS WORK." Pasteur's first care was to seek the cause of what is called spontaneous anthrax, that which appears suddenly in a flock without contact with, sick malsKoch had explained the persistence of the disease in an anthrax country by the resistance of the .spores; he had shown that the malady develops as though it resulted from an infection by the digestive tract, and be had produced infection thus by giving guinea-pigs food sprinkled with bacteridium cultures. He had not experimented on larger animals. Pasteur lesolved to complete these experiments and to transport them from the laboratory to the natural habitat of tho animals. lie had said :—"Une method almost alone has served me as a guide to the study of micro-organisms. It consists essentially in the culture of these minute beings in a pure state, that is, freed from all other materials living or dead which accompany them. By employing this method the most complicated problems sometimes receive simple and decisive solutions." It was once more from this method tliat ho demanded the answer to his question about spontaneous anthrax. To begin with, he fed certain lots of 6heep on lucerne watered with cultures of antnrax bacteridia. In the same lot some sheep died with all the symptoms of spontaneous anthrax; most survived, often after haying shown signs of illness. Tho mortality was increased by mixing with tho lucerne dried thistle leaves and pieces of barley beard, all sharp substances that might erode the mucous membrance and so facilitate the entry of germs.

Eight sheep which had been used for these experiments were then inoculated with cultures, or even with anthraxblood. All were ill, but only one died. Pasteur, recalling that fowls fed with food contaminated with the microbes of chicken-cholera oould, when they did not die, be inoculated in this way, asked himself whether, by an analogous me* thod, sheep could not be vaccinated. The experiment just made already provided an answer.

In the hours of its life the blood of an animal only contains the bacteridium in the form of threads without spores; when the body begins to putrefy this bacteridium, deprived of oxygen, is not long in perishing. Usually, however, at the moment of death the animal Joses blood through the nose or mouth. When it is skinned the blood is spread freely on the soil, and this blood, mixed with air-containing earth, finds conditions favourable to spore production. Generally the carouse is buried, not very deeply, on the spot. Pasteur concluded from this that there ought to be spores on the surface of the graves, and he set himself to the task of verifying; this hypothesis. He suspended in water a little of the earth from a pit dug fourteen months before. It is with the finest particles which are last deposited that the microbes of cultivated soil will be found in milliards. If some of these 4 were planted just as they are, the struggle for existence would certainly not allow any spores which might be found there to develop; but these spores easily resist a temperature of 90 C., which kills most soil microbes. It is sufficient to heat the fine particles of earth to this degree and then inoculate them into guinea-pigs to cause some to die of anthrax, and thus prove the existence of the spores. These were interesting facts, but they did not completely satisfy Pasteur. How do spores remain on the surface of the soil, where they are swept by the rain and carried on the surface of the soil, where ploughing or other methods of cultivation ? Pasteur continued to inquire. His collaborator, Rox, tells how he found the answer during one of his visits to the Chartres neighbourhood:— “The Harvest was carried, nothing remained but stubble. Pasteur's attention was drawn to part of a field by a difference in the colour of the ground. M. Manoury explained that the year before some sheep which had died of anthrax had been buried on this spot Pasteur, who always examined things closely, noticed on the surface of the ground a number of worm-casts. The idea occurred to him that the worms in their constant passage from below carried to tho surface earth rich in the humus which surrounds a dead body, and with it the anthrax spores'which it contains. . . . Pasteur never stopped short at supposition. He proceeded immediately to experiment. This confirmed his anticipation. It reminds me among other things of a demonstration given before Villemin, Davaine and Bouley. The last-mentioned had taken the trouble to send for some worms collected from the earth of a pit where anthrax carcases had been buried many years before. The earth from the intestine of one of the worms gave anthrax to guineapigs on inoculation." These exhumed spores arc eaten by sheep cropping the short grass; they can also be carried as far as the stream where the flock is watered, and may thus come in contact with a scratch which facilitates inoculation.

Pasteur had found the bacteridium in tho earth of graves, and had also discovered that earth taken some yards away did not contain it; but he * was never content with laboratory experiments. He had tho place in a field where two years previously an anthrax cow had been buried enclosed. Four sheep were shut up there. Four other sheep, intended as controls, were placed in a similar enclosure some yards from the first and rather high up. Eight days later one of the sheep in the find enclosure died of anthrax. The control sheep remained perfectly well.