On spontaneous generation and the lack thereof (discussed by the group on 9/4)

Pasteur: The Chemist Who Transformed Medicine
Collection of the University of Michigan Health System
Commissioned by Parke-Davis & Co. in the 1950s as
part of a 45 oil painting series titles 'A History
of Medicine in Pictures' by Robert Thom.

Spontaneous generation, a widely held belief first described in the 5th century BCE, is eloquently explained by Aristotle as organisms  "not derived from living parentage, but [that are] generated spontaneously: some out of dew falling on leaves, ordinarily in spring-time, but not seldom in winter…" was decidedly disproved by recent experiments of Louis Pasteur, a modern scientist of the 19th century. In a series of articles published in the 1860s, the author describes the introduction of "amianthus charged with atmospheric dust" to boiled milk or urine resulting in the growth of bacteria, including "very minute Vibriones, and Monads" leading to putrefaction. The boiled liquid when untouched remained unchanged, suggesting a substance contained on or within the dust promoted the growth of microorganisms. This simple set of experiments led to the confirmation of biogenesis (life from life) and the subsequent discovery that certain microorganisms cause disease (germ theory).

• Aristotle on Spontaneous Generation: Aristotle, The History of Animals, Book 5
• Pasteur on the lack thereof (English translations): Translations: On the Origin of Ferments. New experiments relative to so-termed Spontaneous Generation (1860)
• XXXIV.—A novel instance of the production of fermentation by the presence of Infusoria capable of existing without free oxygen and deprived of all access of atmospheric air (1863)

Note: Here is a free version of the text of the third paper. The Aristotle reading is quite long, so you might want to read just the sections that discuss spontaneous generation, excerpted here. Also, you might be interested to learn about some related, beautiful and well-controlled experiments reported in 1688 by Francesco Redi. -Bob

Other:
Berche, P. (2012), Louis Pasteur, from crystals of life to vaccination. Clinical Microbiology and Infection, 18: 1–6.