evidence: Terrain theory [edit]The terrain theory is a variation of Béchamp's ideas that is also an obsolete medical theory that held that diseases were caused by the composition of the body. The "terrain", will attract germs to come as scavengers of the weakened or poorly defended tissue. Béchamp believed that the pH of the body is important, and that an acidic pH will attract germs and an alkaline pH will repel them. Pasteur disproved spontaneous generation with a series of experiments in the 1870s.[4] However, understanding the cause of a sickness does not always immediately lead to effective treatment of sickness, and the great decline in mortality during the 19th century stemmed mostly from improvements in hygiene and cleanliness. In fact, one of the first movements to deny the germ theory, the Sanitary Movement, was nevertheless central in developing America's public health infrastructure. Providing clean water and sanitation reduced the environment for pathogens to develop, and mortality rates fell dramatically.[8][9][10]