Louis Pasteur, the Columbus of "the world of the infinitely little"—to quote the phrase of Professor Dumas—was born in the town of Dôle, France, on December 27, 1822. His father was an old soldier, decorated on the field of battle, who, after leaving the array, earned his bread as a tanner. In 1825 M. Pasteur moved from Dôle to the town of Arbois, on the borders of the Cuisance, where his son began his education in the communal college. The boy was exceedingly fond of fishing and of sketching, and it was not until he reached the age of fourteen that he began study in earnest. There being no professor of philosophy at Arbois, Louis Pasteur moved to Besançon, where he received the degree of bachelier ès lettres and was at once appointed as one of the tutors. Here he studied the course in mathematics necessary for admission into the École Normale, in Paris, which he entered in October, 1843. Already his passion for chemistry had shown itself, and he took the lectures in that science delivered by M. Dumas at the Sorbonne, and by M. Balard at the École Normale. It was but a short time before he became a marked man in his class, especially for his intense devotion to experiment. Thanks to M. Delafosse, one of the lecturers of the École Normale, his attention was turned to crystallography, and a note from the German chemist, Mitscherlich, communicated to the Academy of Sciences, set him on fire with curiosity. Mitscherlich declared: "The paratartrate and the tartrate of soda and ammonia have the same chemical composition, the same crystalline form, the same angles, the same specific weight, the same double refraction, and the same inclination of the optic axes. Dissolved in water, their refraction is the same. But while the dissolved tartrate causes the plane of polarized light to rotate, the paratartrate exacts no such action."
Pasteur at once instituted experiments resulting in the discovery of minute facets in the tartrate which gave it the power noted. He found in the paratartrate these facets existed, but that there was an equal admixture of right-and left-handed crystals, and the one neutralized the effect of the other. He also discovered the left-handed tartrate. These discoveries at the opening of Pasteur's career brought him at once to the front among the scientific men. He followed them with a profound investigation into the symmetry and dissymmetry of atoms, and reached the conclusion that in these lay the basic difference between inorganic and organic matter, between the absence of life and life.
Nominated at the age of thirty-two as Dean of the Faculté des Sciences, at Lille, Pasteur determined to devote a portion of his lectures to fermentation. At that time ferments were believed to be, to quote Liebig, "Nitrogenous substances—albumin, fibrin, casein; or the liquids which embrace them—milk, blood, urine—in a state of alteration which they undergo in contact with air." Pasteur examined the lactic ferment and found little rods, 1/25000 inch in length, which nipped themselves in the centre, divided into two, grew to full length and divided again, and these living things he declared to be the active principles of the ferment. He made a mixture of yeast, chalk, sugar, and water, added some of the rods, and got fermentation. He then made a mixture of sugar, water, phosphate of potash, and magnesia, and introducing fresh cells, fermentation followed. Liebig's theory of the nitrogenous character of the ferment disappeared when fermentation was caused in a mixture having no nitrogenous elements.
Pasteur had discovered that fermentation was a phenomenon of nutrition; it followed the increase and growth of the little rods. The next step was the discovery of the ferment of butyric acid, a species of vibrio consisting of little rods united in chains of two or three and possessed of movement. He found these vibrios lived without air. Further experiments showed there were ferments to which air was necessary, called by Pasteur the ærobics, and others to whom oxygen was fatal, the anærobics. He proved, also, by an exhaustive series of experiments, that what is called putrefaction of animal matter is the result of the combined work of the ærobics and the anærobics, which reduce that part not taken up by oxygen to dead organic matter, ready in its turn to form food for living things.
His attention having been turned to the needs of the vinegar makers of Orleans, Pasteur began the examination of the ferment which produces vinegar from wine. He found this in the mycoderm aceto, a mould-like plant which has the power of developing acetic acid from alcohol. As the result of his investigation, the manufacturers of vinegar in France were able to do away with the cumbrous process they had long followed, and to make vinegar, not only more cheaply, but of very much better quality. But during these experiments Pasteur found the temperature of 65° C. was sufficient to kill the mycoderm. When, then, the wine makers of France appealed to him to investigate the "diseases" of wine, he was ready for the work.
Before this, however, he had examined the claims of Pouchet and others to their alleged discovery of spontaneous generation; in other words, the production of life. Ranging himself against them, Pasteur showed their experiments not to have been conclusive, simply because they had not succeeded in excluding the dust which contained germs of life in the shape of spores of microscopic plants.
The "diseases" of wine produce sour wine, wine that "spirits," "greasy" wine, and bitter wine. Pasteur found each to be due to a different microscopic ferment, all of which could be killed by heat. He placed bottles of wine in a bath heated to 60° C., and invited the most experienced wine tasters of Paris to try them afterward. The result of the test was the unanimous verdict that the wines had not been injured in the least, and to-day these "diseases" of wine are a thing of the past.
There are departments in France where the culture of the silk-worm is the principal industry of the inhabitants. In 1849 a strange disease, called pebrine, broke out among the worms; they were unable to moult and died before the cocoons were spun. It spread in the most alarming manner until, from a crop with an average of one hundred and thirty million francs a year, the production of silk went to less than fifty millions. The silk cultivators sent for eggs—seed is the technical name—to Italy and Greece, and for one season all went well. The next, the plague was as bad as ever. More than that, it spread to Italy, Spain, Greece, and Turkey, until Japan was the only silk-producing country where the worm was healthy. Societies and governments, as well as individuals, were aghast, for the silk industry of the world was on the verge of annihilation, and every remedy the mind of man could conceive was tried, only to be rejected. In France alone the loss in 1865 was over one hundred million francs.