The power of his mind, the radiating gifts that he possessed, were such that his own people were more and more interested in the laboratory, every one trying day by day to penetrate further into Pasteur’s thoughts. His family circle had widened; his son and his daughter had married, and the two new-comers had soon been initiated into past results and recent experiments. He had, in his childhood and youth, been passionately loved by his parents and sisters, and now, in his middle age, his tenderness towards his wife and children was eagerly repaid by the love they bore him. He made happiness around him whilst he gave glory to France.
CHAPTER X
1880—1882.
A new microbe now became the object of the same studies of culture and inoculation as the bacillus anthracis. Readers of this book may have had occasion to witness the disasters caused in a farmyard by a strange and sudden epidemic. Hens, believed to be good sitters, are found dead on their nests. Others, surrounded by their brood, allow the chicks to leave them, giving them no attention; they stand motionless in the centre of the yard, staggering under a deadly drowsiness. A young and superb cock, whose triumphant voice was yesterday heard by all the neighbours, falls into a sudden agony, his beak closed, his eyes dim, his purple comb drooping limply. Other chickens, respited till the next day, come near the dying and the dead, picking here and there grains soiled with excreta containing the deadly germs: it is chicken cholera.
An Alsatian veterinary surgeon of the name of Moritz had been the first to notice, in 1869, some “granulations” in the corpses of animals struck down by this lightning disease, which sometimes kills as many as ninety chickens out of a hundred, those who survive having probably recovered from a slight attack of the cholera. Nine years after Moritz, Perroncito, an Italian veterinary surgeon, made a sketch of the microbe, which has the appearance of little specks. Toussaint studied it, and demonstrated that this microbe was indeed the cause of virulence in the blood. He sent to Pasteur the head of a cock that had died of cholera. The first thing to do, after isolating the microbe, was to try successive cultures; Toussaint had used neutralized urine. This, though perfect for the culture of the bacillus anthracis, proved a bad culture medium for the microbe of chicken cholera; its multiplication soon became arrested. If sown in a small flask of yeast water, equally favourable to bacteridia, the result was worse still: the microbe disappeared in forty-eight hours.
“Is not that” said Pasteur—with the gift of comparison which made him turn each failure into food for reflection—“an image of what we observe when a microscopic organism proves to be harmless to a particular animal species? It is harmless because it does not develop within the body, or because its development does not reach the organs essential to life.”
After trying other culture mediums, Pasteur found that the one which answered best was a broth of chicken gristle, neutralized with potash and sterilized by a temperature of 110° C. to 115° C.
“The facility of multiplication of the micro-organism in that culture medium is really prodigious,” wrote Pasteur in a duplicate communication to the Academies of Sciences and of Medicine (February, 1880), entitled Of Virulent Diseases, and in particular that commonly called Chicken Cholera. “In a few hours, the most limpid broth becomes turgid and is found to be full of little articles of an extreme tenuity, slightly strangled in their middle and looking at first sight like isolated specks; they are incapable of locomotion. Within a few days, those beings, already so small, change into a multitude of specks so much smaller, that the culture liquid, which had at first become turgid, almost milky, becomes nearly clear again, the specks being of such narrow diameter as to be impossible to measure, even approximately.
“This microbe certainly belongs to quite another group than that of the vibriones. I imagine that it will one day find a place with the still mysterious virus, when the latter are successfully cultivated, which will be soon, I hope.”
Pasteur stated that the virulence of this microbe was such that the smallest drop of recent culture, on a few crumbs, was sufficient to kill a chicken. Hens fed in this way contracted the disease by their intestinal canal, an excellent culture medium for the micro-organism, and perished rapidly. Their infected excreta became a cause of contagion to the hens which shared with them the laboratory cages. Pasteur thus described one of these sick hens—
“The animal suffering from this disease is powerless, staggering, its wings droop and its bristling feathers give it the shape of a ball; an irresistible somnolence overpowers it. If its eyes are made to open, it seems to awake from a deep sleep, and death frequently supervenes after a dumb agony, before the animal has stirred from its place; sometimes there is a faint fluttering of the wings for a few seconds.”