Lecture 13 - Germs.docx

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Western University
History of Science
History of Science 2220
Dorotea Gucciardo

January 16, 2013 [THE “GERM” THEORY] EXAM Germs  Refers to bacteria, viruses, parasites, fungi, etc. Focus on bacteria.  The belief that germs exist is one of the most widely accepted precepts in Western medicine. The belief is so engrained that it almost defies logic that people at one point didn’t believe in them.  The Germ Theory of Disease has considerations: o Came into common use in the English language in the 1870’s. o Scientific shorthand to refer to the people that were most relevant in the development of that theory. The people that were most relevant were between the 1860’s to 1910’s. o The germ theory of disease consists of two propositions: 1) Animal and human diseases are caused by a distinctive species of micro-organisms. These organisms are present in the air and water. 2) Germs could not generate spontaneously. They had to come from a previous case of the exact same disease. o Some believers did not believe that germs were not spontaneously produced. They believed that under the right environmental conditions, disease germs might spontaneously appear. This reflects the miasmic theory.  People in Western society knew of the existence of various diseases, and that sufferinthfrom these diseases was transmittable – an intangible substance – but didn’t understand it. By the 18 century, breath, skin, clothing, evacuations can spread disease – idea of contagiousness. By the th 19 C, Western world people were not very concerned about contact with sick people.  Any changes in habits came from etiquette books. Part of proper etiquette included not spitting or coughing in public – advocated personal cleanliness. However this was more about presentation that preventing spreading of germs/not from fear of disease.  Members of Western society viewed disease as inherent – hereditary combined with living circumstances. E.g. of this attitude: tuberculosis. th  In the late 19 C, more people were becoming nervous about disease outbreaks, and municipalities began keeping death rate statistics. This confirmed climbing death rates and unhealthy conditions. People were thrown into crisis from endemics AND pandemics.  The scientific community attempts to understand the spreading of diseases.  Louis Pasteur (1822-1895) o Chemist – not physician. o Trained in Paris and in the 1850’s got a job in an industrial town in France. Hired to investigate the needs of the local industries (alcoholic industries – vinegar, wine, etc.). He investigated the process of fermentation – when an organism is converting a carbohydrate into an alcohol. He uses his microscope to do so, concluding that the agents of fermentation and putrefaction came from different species of living organisms. (Putrefaction = the process of decay/composition.) o These processes were important to brewers and vinegar producers. Pasteur became an expert in fermentation. He pioneered methods of experimentation. He used microscopes to examine broths in flasks. They were wide at the base and long at the necks – the air would escape from the flasks but the organisms were too heavy and stayed in the jar. He realized that some of these species were aerobic (needing air to live) while others were January 16, 2013 [THE “GERM” THEORY] anaerobic (thrive in the absence of air). He also discovers that these microbes could be removed by boiling and cooling a liquid: pasteurization. He then realizes that he can get rid of potential germs through this method, sensing the importance of this beyond his industry. o Now he examines where they potentially come from. He referred to these microbes as bacteria by the 1860’s. *Antonie van Leeuwenhoek  First observed the existence of bacteria.  By the 1820’s the term bacteria is coined.  By the 1860’s Pasteur adopted the term. o Proved that bacteria came from the environment, essentially putting forward the germ theory. Argued that microorganisms were responsible for disease and that being able to distinguish between these organisms allowed for the prevention of disease to occur. He publishes these ideas. The germ theory was contested because some still believed that germs could be spontaneously produced. By legitimizing this theory he also does so to the science of bacteriology. This gained widespread acceptance by the 1880’s. o Gains support from some scientific institutions, but some follow it like a religion. They see the world as a place where air, soil, and water are teaming with invisible life – there is much beyond what can be seen by the naked eye. o Up until this point, doctors were using stethoscopes to determine sickness and disease occurrence. This theory marks the process of diagnosis from taking place at the bedside to the laboratory – using a microscope. From 1865-1895 there is constant debate as to the legitimacy of the germ theory.  Joseph Lister o When Pasteur came out with his theory, Lister wondered if germs in the air in operating rooms contributed to infections occurring after surgeries. o Taking Pasteur’s principles, and is one of the first people to try and sterilize the operating room…to much success. There is a dramatic decline in the infection of post-operated wounds. o Helps to legitimize the germ theory.  By 1900(‘s) dramatic progress was made. For th
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