Louis Pasteur (S01E09)

In 1860, a cholera outbreak threatens France's chicken population. Louis Pasteur and his assistant, Emile Roux, gather samples and conclude that the disease spreads through the air. While examining the blood of the chickens, they identify an unknown germ. Suddenly, Pasteur suffers a severe stroke, but from his sickbed, he remains determined to continue his work, communicating with Roux through notes. He instructs Roux to inject the contaminated blood into the chickens, resulting in their deaths. Upon returning to the lab, Pasteur discovers the blood has changed over time. When they re-inject it into the chickens, it successfully eradicates the cholera germs, leading to the creation of a vaccination. Meanwhile, an anthrax outbreak begins affecting sheep, and despite skepticism from other scientists, they permit Pasteur to test his methods on 25 sheep.