Fanny Hesse

Originally published on Technicians Make it Happen June 2019. Below is the full version.

  • Name: Fanny Angelina Hesse (also known as ‘Lina’)
  • DOB: 22 June 1850
  • DOD: 1st December 1934 (Age 84)
  • From: New York, USA
  • Area of work: Bacteriology
  • Without her…: Without Fanny’s introduction of agar the study of bacteria, the understanding of disease, and even the clinical diagnosis of disease would not have made the rapid progress we have seen in the last hundred years.
Fanny Hesse
Fanny Hesse

What she did

Polenta, potato, gelatin, and coagulated egg white. No, not a school dinner menu from hell, but some of the materials used as solid surfaces on which to grow and study bacteria in the early days of bacteriology. All of these had significant disadvantages, so when laboratory technician Fanny Hesse suggested the use of agar, it revolutionized this burgeoning new area of science. Even the great Louis Pasteur exclaimed, “C’est un grand progrès!”

Fanny was born in 1850 in New York, daughter of a successful Dutch immigrant. Little is known of her early life but in 1872, Fanny met her future husband Walther, then serving as a ship’s surgeon on a German passenger liner. The couple were married on 16th May 1874 and Fanny moved to Dresden to be with her husband.

Walther was a country doctor who was passionate about hygiene and public health for workers, particularly the conditions of workers in the local mines. In 1881 he took a sabbatical to study in the Berlin labs of Robert Koch, the ‘father of bacteriology’, to investigate airborne microorganisms.

On top of her duties running the household and the education of their sons, Fanny became Walther’s assistant. She worked as an unpaid technician, preparing bacterial growth media (normally beef broth), cleaning equipment, and using her considerable artistic talents to produce beautiful watercolour illustrations for his publications.

Fanny and Walther Hesse
Fanny and Walther Hesse (taken from paper Hitchens & Leikind 1939 – details below)

To study airborne microbes, Walther was using tubes lined with the growth media made by Fanny. Unfortunately, the gelatin used to solidify this media melted at 37°C and would liquify on warm days. Similarly, some bacteria broke down the gelatin to liquid. These issues plagued their experiments and were a source of great frustration.

Fanny suggested replacing gelatine with the seaweed extract agar-agar. She had been using agar for years in the preparation of fruit and vegetable jellies using recipes from her mother, who had in turn obtained the formula from some Dutch friends who had lived in Java, Indonesia.

Agar solved their problems: solid up to 90°C, transparent, indigestible by microorganisms, and sterilizable, it was perfect for growing and studying bacteria. Walther told Koch and he immediately saw the benefits. In his 1882 paper, Koch states, “The tubercule bacilli… grow, for example, on a gelatinous mass which was prepared with agar-agar, which remains solid at blood temperature…” No mention of either of the Hesses was made in that paper.

Walther himself published many papers in his lifetime, not only on bacteriology but on hygiene and public health issues. His last publication in 1908 described method of culturing intestinal bacteria from typhoid fever patients. Fanny painted beautiful and highly accurate images of the magnified colonies on agar plates during different growth phases using watercolours; work that was only possible if she had a thorough understanding of both bacteriology and microscopy. Despite her contribution to this and many more of Walther’s papers she was never included as author or acknowledged in his work.

Agar has become almost as important to bacteriology as the petri dish, which would be invented just a few years later. Despite this, when Fanny died in 1934, few bacteriologists knew of her death. In their 1939 paper on Fanny’s life, Hitchens and Leikind suggested that “plain agar” be referred to as “Frau Hesse’s medium” to acknowledge her forgotten “service to science and to humanity.” This is yet to happen, but it is never too late.


The great news is that Fanny has her own Wikipedia page! There are lots of places you can read more about Fanny. I have included a selection below:

  • P. Mortimer, Koch’s colonies and the culinary contribution of Fanny Hesse, Microbiology Today, 28(AUG), 136-137 (2001)
  • A.P. Hitchens and M.C. Leikind, The introduction of agar-agar into bacteriology, Journal Bacteriology, 37(5), 485–493 (1939)
  • C. Agapakis, The forgotten woman who made microbiology possible,, (2014),
  • W. Hesse, Walther and Angelina Hesse-Early Contributors to Bacteriology, Translated by D.H.M. Groschel, ASM News, 58(8), 425-428, (1992)
  • C.M.C Haines, International Women in Science: A Biographical Dictionary to 1950, (2001)

Walther’s 1908 paper that is mentioned in the text is:

  • W. Hesse, Ein neues Verfahren zur quantitativen Bestimmung der Darmbakterien, mit besonderer Berücksichtigung der Typhusbazillen , Zeitschrift für Hygiene und Infektionskrankheiten, 58(1), 441–448, (1908)

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