Walther Hesse is best known for his work in microbiology, specifically his work in developing agar as a medium for culturing microorganisms.
Education
Born in Bischofswerda, Lusatia, as one of 12 children in the family of a medical practitioner, Hesse attended the Kreuzschule in Dresden and studied medicine at the University of Leipzig with Ernst Leberecht Wagner from 1866 till 1870, when he received his doctorate in pathology.
Career
Afterwards he participated in the Franco-Prussian War, and therein in the Battle of Gravelotte. After some years as a medical practitioner in Pirna and Zittau, Hesse went to Schwarzenberg, Saxony in 1877. His investigations in Schneeberger Bergkrankheit, responsible for the commonly early death of miners in the Ore Mountains, are credited as the first unveiling of working conditions as cause of an interior disease (lung cancer).
Within his time in Schwarzenberg, he took a year with Max Joseph von Pettenkofer at Munich to deepen his knowledge in occupational hygiene.
Hesse joined Robert Koch"s laboratory (effectively in a post-doctoral position) in 1881 to study air quality. He was convinced that microorganisms were present everywhere, even in water and in the air.
He used a series of filters, made mainly from wadding, in attempts to capture and observe microorganisms. When culturing the organisms he trapped with his filter, he used a gelatin-containing medium capable of solidifying.
Frustratingly, the medium had a tendency to melt during the summer months, thus ruining the experiments.
Additionally, many of the organisms he cultured were capable of degrading the gelatin medium, also ruining his experiments. When asked why this was so, Lina (as she was called) replied that they contained agar, and that she had been shown the trick by a Dutch neighbor (recently emigrated from the island of Java, in the Dutch East Indies(Indonesia)) when she was growing up. Further development of agar showed that it would not easily melt (though would remain molten at lower temperatures once it did), was not easily degraded by microorganisms and was a flexible medium.
Koch was soon using the new medium to grow tuberculosis bacteria.
In later years, Hesse was district physician in Dresden. He continued his scientific works, experimented with Petri dishes and investigated the microbiological foundations of typhus, cholera and diphtheria.
He operated a laboratory at the Technical College Dresden together with Walther Hempel. Hesse introduced pasteurization of milk in Pfund"s dairy.
The family"s tomb at the cemetery of Serkowitz was created by Arnold Kramer.