Before the idea that germs can invade your body and make you sick, people thought that illnesses were a punishment from God or a punishment for a person's bad behavior. Sometimes large amounts of people died at one time and the people blamed it on swamp vapors or foul odors from sewage. Even the more educated people believed that illness was caused from poisonous vapors from planetary movement or effects from within the earth. In the seventeenth and eighteenth centuries, tools were made and techniques were designed that could permit scientists to study bacteria
There were many experiments which lead to the germ theory. All in which needed special instruments for examinations and tests. Robert Hooke and Anton van Leeuwenhoek invented microscopes for scientists to use in the seventeenth century. This allowed them to observe tiny bacteria and microorganisms.
Francisco Redi was famous for disproving the theory of spontaneous generation (of maggots from meat) in his meat experiment. he put different types of meat in sealed jars for three weeks. "the meat and the fishes inside the open flasks became verminous, and after three weeks I saw many flies around these flasks, but in the locked ones I've never seen a worm ". -Francisco Redi.
Lady Montague introduced the practice of variolation to England in the seventeen hundreds and Edward Jenner soon after improved this practice. Lady Montague observed women practice a prevention of smallpox with a less virulent smallpox virus and Jenner noticed that women who contracted cowpox rarely got smallpox.
Ignaz Semmelweis noticed that fatal infections found in maternity patients in the Viennese Hospital could be prevented with simple hygiene. To prevent these infections, the doctors washed their hands in chlorinated lime water before they examined pregnant women. Many physicians did not agree with the germ theory and thought that this practice was useless.
John Snow started epidemiology when he closed off the Broad Street Pump because the contaminated water was the cause of cholera epidemic. Physicians still didn't want to believe that an invisible organism could spread disease.
Louis Pasteur, probably the most famous for the germ theory discovery, did an experiment were he discovered the "diseases" of wine and beer. We get the word pasteurization from him when he discovered that you can heat a product just enough to kill bacteria, but not enough to do anything to the yeast. This connection of food spoilage and microorganisms was a link to microorganisms and diseases. Said that microorganisms in the air can contaminate what seems to be pure substances. Also demonstrated beef broth experiment - broth with an open flask was infected with microorganisms and the sealed ones were not.
Rudolf Virchow introduced biogenesis - concepet that living cells come from living preexisting cells.
Agostino Bassi did a silkworm experiment where they showed silkworm diseases were caused by microorganisms -caused by contact and infected food. In 1876, Robert Koch proved that bacteria caused diseases. Koch helped destroy the theory of spontaneous generation and started a foundation for modern microbiology.
Joseph Lister started the earliest attempt to control infectious microorganisms by soaking surgical dressings in carbolic acid for prevention of prosperitive infection.
Proof that a particular organism causes a particular disease:
1. The organism must be present in every case of the disease.
2.The organism must be isolated from a host with the corresponding disease and grown in pure culture.
3.Samples of the organism removed from the pure culture must cause the corresponding disease when inoculated into a healthy, susceptible laboratory animal.
4.The organism must be isolated from the inoculated animal and identified as being identical to the original organisms isolated from the initial, diseased host.
The characteristics of several of the forms of fermentation were given. In vinous fermentation the stages in the change are as follows:
1.The liquid grows turbid.
2.Bubbles are seen to rise as gases are given off.
5.The liquid becomes clear and lighter in color, and a sediment forms at the bottom of it.