Louis Pasteur, Conqueror of Disease
- E. H. Carter
On the field of battle in one of his campaigns, Napoleon decorated for bravery a certain tanner named Pasteur. This brave soldier had an equally brave son, Louis Pasteur, born seven years after Waterloo. He was not a soldier, but he was a fighter.
He fought disease. He devoted his life to the study of what we sometimes call germs, which men of science call bacteria, a Greek word meaning ‘little rods.’ Bacteria are vegetable organisms – little rod-shaped plants – which exist in the air, water and soil, and in the bodies of animals and plants; some but not all are the causes of diseases, some convert matter into food for plants.
Louis Pasteur had a very busy and interesting life. He not only made some exciting discoveries about germs but he was able to use his discoveries in very practical ways. He worked hard in his laboratory with test tubes and all kinds of experiments, but nearly all the time he was working to help people who were suffering in some special way from disease. Among the people whom Pasteur was able to help were brewers, breeders of silk worms, and cow keepers, all of whom were trying to carry on important industries in France. Pasteur was always very proud of being able to help his country in this way.
Louis Pasteur, born in a little French country town, was interested in chemistry when he was very young. After studying hard in Paris and showing great promise, he began to teach and lecture as Professor of Chemistry. He became a Professor at Strasburg in Alsace, and he married a wife who was always to be his closest companion and assistant.
Pasteur was deeply interested in all the new experiments that were being made in chemistry, and decided to solve some of the difficult problems that were worrying chemists and other scientists. Sometimes he used to sit for hours, quite silent and motionless, thinking hard about one of his difficulties. He found this the easiest way to solve a problem; and when he thought of a solution, his kind, tired looking face would brighten with pleasure and excitement and he would rush round to tell his discovery to his wife and to others who were helping him.
In 1854 Pasteur was appointed Head of a College of Science at Lille, a busy manufacturing town in the north-east of France. He was pleased about this, because he always felt that trades and industries could be helped very much by the researches of men of science. His chance to be useful soon came.
Pasteur, as a young chemist, had always been interested in the problems of why and how living things decay, why milk turns sour, why meat goes bad, why wine ferments. He started to give some lectures in Lille on fermentation. One of the chief industries in Lille was the manufacture of alcohol from beetroot, and he was fortunate in being able to carry out experiments in some of the breweries. One manufacturer consulted Pasteur about his beer, which was turning out badly, and Pasteur by helping this brewer managed to discover all sorts of things that he did not know before about yeast. Yeast is used to make beer foam and bread rise up lightly. Pasteur became certain that yeast was alive, made up of tiny living cells. When these cells were healthy the yeast acted well, but if they were diseased, the yeast and the beer went wrong.
After a few years, Pasteur was made Director of Scientific Studies at a famous college in Paris. He was still thinking about decay and yeast and germs and one of the problems that he was trying to answer was this : “Do germs form from other germs, or do they just come of themselves?” People like Pasteur believed that germs were carried in the air and might infect other things that came in contact with them. Others believed in what they called “spontaneous generation” – i.e., they believed that germs had no parents but just occurred by themselves.
Pasteur proved that he was right by a very simple and clever experiment. He put some soup into some bottles and then he boiled it in order to destroy any germs that might already be in the soup. After that he heated and pulled out the neck of each bottle until it formed a long narrow ‘neck’ with a big bend in the middle. The soup remained there for a long time and it never went bad as it would have done if it had been standing in a bowl in the kitchen. “That,’’ said Pasteur, “is because there are no parent germs in the soup, and they cannot reach it because of the bend in the long tube.” So, he took one of the bottles and spilt a little of the soup down the tube so that it settled in the bend. This soup went bad. We often speak of "dust traps." Well, this bend in the tube was a dust trap, because the dust – which, as we now know, may carry germs with it - could get as far as the bend but no farther, and it settled there and infected the soup.
This is only one of many hundreds of experiments which Pasteur made to show how full the air is of dust particles and how germs may be carried by this dust. One very useful experiment was made to show the difference between pure and stale air. Pasteur again filled some bottles with soup. He took some into a little hotel bedroom where the air hardly ever changed, broke their necks off so that the air could enter freely, and after a few minutes sealed them up again. He then took some bottles into a field near by and did the same with them. Finally he opened some on the top of a high mountain and again sealed them up. What was the result? When they were examined, the bottles opened in the hotel bedroom were full of soup which had gone completely mouldy; the bottles opened in the field were mouldy, but not quite so bad; those opened on the mountain had no germs in them at all.
Nowadays, we pay a great deal of attention to pure air, open windows, to freedom from dust, to garden cities. Pasteur was one of the first to show how necessary all these are if we are to fight against germs and disease.
Another very useful discovery of Pasteur’s while he was working in Paris was the process which we now call, after him, "pasteurization". Some French wine-growers were troubled by a germ which had turned their wine sour. Pasteur showed that by heating the wine, or milk, or whatever it might be to a temperature of 50 or 60 degrees centigrade, the germs were made harmless. Pasteurized milk is milk which has been treated in this way and then sealed to prevent more germs from entering.
Louis Pasteur was what we should call an "all round" scientist. All the research which he did in his laboratories was meant to help his fellow human beings. It would be impossible to imagine Pasteur experimenting with explosives or poison gas.
Pasteur founded the branch of science called "bacteriology", or the study of bacteria, and he showed what a wide range it had by studying the bacteria in all sorts of different activities. For three years he spent all his time and energy in tracking down the cause of a disease which had ruined the silkworm industry. He began to believe that most, if not all, infectious diseases were due to certain bacteria which, if they got into the blood, multiplied there and caused disease.
Many other men were working and experimenting against those bacteria which were the enemies of man and which were invisible but present everywhere and always ready to attack. Dr. Jenner in England had already discovered vaccination for smallpox, but ‘inoculation’ against other diseases had not yet started.
Pasteur was trying to discover a cure for the terrible disease called anthrax, which men sometimes get from infected shaving brushes, and which was attacking cows and sheep in France and killing them off very quickly. He found out first of all that a cow could not have anthrax twice. Then he began to wonder whether it would not be possible to make a cow and even a man just a little ill with anthrax, so that they might not get it again. Perhaps this could be done by giving the cows or sheep very weak old germs to make them safe or ‘immune’ for the future. One can imagine how dangerous this idea of giving people germs must have seemed in those days. Many scientists were angry about it, but they agreed to allow Pasteur to prove it by a public experiment.
So, Pasteur collected some sheep, goats and cows, and divided them into two lots. To one lot he gave injections of his weak anthrax germs. The other lot was left alone. Then on a certain day all the animals were injected with the most deadly anthrax germs that could be produced. On the third day after the experiment, a crowd of people gathered round the sheds to see what had happened to the animals. Pasteur, even though he was so sure of himself, must have felt nervous. All the two dozen animals that had first been protected by the weak germs were perfectly well. The deadly injection had done them no harm at all. Of the other two dozen animals, twenty-two were dead and the other two were dying. When the news spread that Pasteur had discovered a cure for anthrax, hundreds of people wrote to him for supplies of “vaccine” or weak germs, and he had to turn his laboratory into a kind of small germ factory.
Pasteur received many honours from the French Government, and in 1881 he came to a big medical Congress in London. When he walked down the hall, there was a storm of applause. He looked round, thinking that the cheers must be for some royal person, for Pasteur could hardly believe that the applause was meant for him.
One of his last experiments was in connection with the terrible disease which attacks a person who is bitten by a dog with rabies, a ‘mad’ dog as we call it. Pasteur had grown very sure about the power of inoculation, and he decided to try out the same idea in cases of rabies. At that time nearly every one died who was bitten by a diseased dog. In 1885 Pasteur made his first experiment on a young Alsatian boy who came to him in Paris covered with bites from a mad dog. The boy’s mother told Pasteur, “If you can cure animals, you can cure my son.” So Pasteur inoculated him with some weak rabies germs and the boy recovered.
Although Dr. Jenner had already discovered how to vaccinate against small pox, he did not really understand about bacteria. Pasteur after giving his life to this study was able to prove the value of inoculation, and to find out ways of varying it for different diseases.
During the First World War (1914-18), the troops going abroad were inoculated against such diseases as typhoid and enteric fever, and the very low death-rate from these illnesses among the troops, even in unhealthy places, was a great tribute to Pasteur’s work.
Pasteur’s memory is still honoured in the Institute Pasteur in Paris, where bacteriology is studied by men of all nations. At the opening of the Institute in 1888, Pasteur said, “Two opposing laws seem to me now in contest – the one, a law of blood and death, opening out each day new methods of destruction, forces nations to be always ready for the battle; the other, a law of peace, work and health, whose only aim is to deliver man from the disasters which surrounded him. The one seeks violent conquests, the other the relief of mankind..... Which of these two laws will prevail God only knows; but of this we may be sure, that science in obeying the law of humanity will always labour to enlarge the frontiers of life.”
Someone who knew Pasteur well in his old age described him thus: “Weary, with deep lines on his face, the skin and beard both white, his hair still thick and nearly always covered with a black cap; the broad forehead wrinkled, marked with the lines of genius, the mouth slightly drawn by paralysis, but full of kindness..... and above all, the living thought which still flashes from the eyes beneath the deep shadow of the eyebrows.”
On Pasteur’s 70th birthday his jubilee was celebrated almost like a national festival. Like Lord Lister, he was honoured in his old age by the scientists of all nations. At the crowded meeting in the great hall of the University of Paris, the old man was too overcome to speak, and his speech was read to the distinguished audience by his son.
“The future,” he said, “will belong to those who shall have done the most for suffering humanity.” To the young students he addressed a special word, ‘First ask yourselves, “What have I done for my education?” Then as you advance in life, “What have I done for my country?” ‘so that some day that supreme happiness may come to you, the consciousness of having contributed in some measure to the progress and welfare of humanity.’
Pasteur himself certainly knew that happiness. He died in 1895 when he was 75, and no name in science is more honoured or will longer be remembered.
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