SAT写作经典例子之化学家巴斯德_SAT写作

SAT写作经典例子之化学家巴斯德

　　In 1847 at the age of 26, Pasteur did his first work on molecular asymmetry, bringing together the principles of crystallography, chemistry and optics. He formulated a fundamental law: asymmetry differentiates the organic world from the mineral world. In other words, asymmetric molecules are always the product of life forces. His work became the basis of a new science --stereochemistry.

　　Research on Fermentation and Spontaneous Generation

　　At the request of a distiller named Bigo from the north of France, Pasteur began to examine why alcohol becomes contaminated with undesirable substances during fermentation. He soon demonstrated that each sort of fermentation is linked to the existence of a specific microorganism or ferment -- a living being that one can study by cultivation in an appropriate, sterile medium. This insight is the basis of microbiology.

　　Pasteur delivered the fatal blow to the doctrine of spontaneous generation, the theory held for 20 centuries that life could arise spontaneously in organic materials. He also developed a germ theory. At the same time, he discovered the existence of life without oxygen:

　　Fermentation is the consequence of life without air. The discovery of anaerobic life paved the way for the study of germs that cause septicemia and gangrene, among other infections. Thanks to Pasteur, it became possible to devise techniques to kill microbes and to control contamination.