Spontaneous Generation

1. Spontaneous Generation • Major biological advancements were made in Europe during the Renaissance (about AD 1300 to 1650). The serious study of anatomy emerged in the 1500s through the efforts of Leonardo da Vinci and Andreas Vesalius, who documented the relationships between the anatomies of humans and of other animals. Advances in anatomy and physiology were made by means of dissection of organisms during the 16th and 17th centuries. • Prior to the 16th century, it was commonly believed that organisms such as flies and worms arose from mud or other inanimate substrates. Although some scientists had previously disputed this idea of spontaneousgeneration, the concept remained untested. In 1668 the Italian physician Francesco Redi was the first to challenge the concept using a set of controlled experiments. (See alsoRedi, Francesco.) • Interest in botany also increased during the 16th and 17th centuries. Numerous papers published by botanists such as Otto Brunfels of Germany and GaspardBauhin of Switzerland discussed horticulture and other plant-related topics.

2. Francesco Redi(1626–97). The 17th-century Italian physician Francesco Redi cast the first serious doubts on the theory of spontaneousgeneration. He demonstrated that maggots develop in rotting meat not spontaneously but rather from eggs laid on the meat by flies. Redi was born on Feb. 19, 1626, in Arezzo, Italy. He read in a book on generation by physician William Harvey a speculation that vermin such as insects, worms, and frogs do not arise spontaneously, as was then commonly believed, but from seeds or eggs too small to be seen. In 1668, in one of the first examples of a biological experiment with proper controls, Redi set up a series of flasks containing different meats, half of the flasks sealed, half open. He then repeated the experiment but, instead of sealing the flasks, covered half of them with gauze so that air could enter. Although the meat in all of the flasks rotted, he found that only in the open and uncovered flasks, which flies had entered freely, did the meat contain maggots. Although he correctly concluded that the maggots came from eggs laid on the meat by flies, Redi, surprisingly, still believed that the process of spontaneousgeneration applied in such cases as gall flies and intestinal worms. (See alsoEvolution.) Redi is also known as a poet, chiefly for his Bacco in Toscana (1685; Bacchus in Tuscany). He died on March 1, 1697, in Pisa, Italy.

3. Lazzaro Spallanzani • A creative and endlessly inquisitive researcher, the Italian physiologist Lazzaro Spallanzani advanced the study of animal biology and animal reproduction. His investigations into the development of microscopic life in nutrient-culture solutions helped disprove the theory of spontaneous generation and paved the way for the research of Louis Pasteur (see Evolution; Pasteur) • Spallanzani devoted all of his leisure time to scientific research, and the range of his interests proved expansive. In 1767 he published his first biological work, an attack on spontaneous-generation theory buttressed by his own experimental results. In 1768 he published the results of a number of regeneration and transplantation experiments. His transplantation experiments showed great experimental skill.

4. Pasteur, Louis • Proof that microorganisms are not generated spontaneously came in the 1860s, when Louis Pasteur, a French scientist, showed that they, too, develop from preexisting life (seePasteur, Louis). • The French chemist Louis Pasteur devoted his life to solving practical problems of industry, agriculture, and medicine. His discoveries have saved countless lives and created new wealth for the world. Among his discoveries are the pasteurization process and ways of preventing silkworm diseases, anthrax, chicken cholera, and rabies. • Pasteur sought no profits from his discoveries, and he supported his family on his professor's salary or on a modest government allowance. In the laboratory he was a calm and exact worker; but once sure of his findings, he vigorously defended them. Pasteur was an ardent patriot, zealous in his ambition to make France great through science

5. Using the four readings before this: • Write the definition of spontaneous generation. • Draw a timeline showing the year of each scientists major discovery and describe their discovery. • Draw a picture on that date that shows the experiment they conducted. • Write at the end of the timeline what scientists believe about spontaneous generation in 2012 and how cells reproduce.