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Gardens of Dust

Just as household bacteriologists used kitchen experiments to instruct ordinary Americans about germs, so too can we reproduce these experiments to let students discover the complexities of turn-of-the-century germ theory for themselves.

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, Selected Dust-Gardens from Household Bacteriology, 1907 (S. Maria Elliott, Household Bacteriology (Chicago: American School of Home Economics, 1914) 99, 101, and 103 | Public Domain)

At the turn of the 20th century, American housewives became increasingly anxious about germs. As public health officers and nonprofits like the National Tuberculosis Association drew attention to the risks of communicable diseases and the importance of domestic sanitation, homemakers sought expert advice to protect the health of their families and communities. This popular demand, coupled with the efforts of microbiologists and home economists to apply their research to daily life, rapidly established a new subfield: household bacteriology. Equipped with basic kitchen equipment, students of household bacteriology learned how to prepare homemade plate cultures called “dust-gardens” to test their belongings and environments for microscopic pathogens. 

This movement to domesticate microbiology left behind numerous sources for the related histories of Progressive-Era public health, education, and activism ranging from course catalogues and textbooks to administrative records and newspaper articles. Aside from student testimonials, however, few of these materials captured the lived experiences of the women who practiced household bacteriology. My unanswered questions about these experiments led me to replicate them in the winter of 2018, cultivating germs to partly recover the experiences of women of the past and to fill some of these archival silences. 

  Over the past decade, Lawrence M. Principe, Elaine Leong, and others have reproduced alchemical tests, home recipes, and material technologies to affirm and occasionally challenge the evidence of more conventional text-based sources. Historians of education have likewise started to extend their research from the curriculum of science classes to their spaces, activities, and apparatus. These projects ask how people from particular historical contexts learned about science, medicine, and technology inside and outside of the classroom, and they offer exceptional opportunities to make history more tangible for students. Engaging with household bacteriology in a similar way shows historical reconstructions as a valuable means to assess educational experiments and to view their results firsthand. What is more, preparing and planting dust-gardens helped me fully appreciate the advantages and limitations of adapting laboratory microbiology to the home.


Although household bacteriologists considered sterilization equipment, laboratory-grade glassware, chemical stains, and microscopes essential for studying microbes, educators such as Sophronia Maria Elliott (1854–1942) nevertheless encouraged ordinary Americans to turn their “kitchens into laboratories and try some simple experiments.” Employing the Progressive Era precept of “learning by doing,” these experiments familiarized homemakers with yeasts, molds, and bacteria, and incorporated this knowledge into routine housework. From the 1890s to 1930, household bacteriology reconfigured tens of thousands of homes into makeshift classrooms for women without the time, money, access, or inclination to learn about germs in high schools or universities. Unable to find any assignments, diaries, or letters from these students about their work, I decided to perform their tests myself.

The directions from Elliott’s 1907 Household Bacteriology, which served as the model for later materials on the subject for home economists and homemakers, seemed straightforward enough. According to the textbook, I could either buy Petri dishes for my dust-gardens or make the required containers myself out of shallow bowls covered with thin panes of glass. As for the beef gelatin used as the “soil” for my cultures, the instructions continued, I would need to “chop finely one-quarter pound of lean, juicy beef,” mix it with “one cup of warm water,” and heat the broth with a double-boiler. The final nutrient medium also contained baking soda to neutralize the acid from the meat and three tablespoons of Knox gelatin. 

After cooking this mixture on the stove and straining it through a layer of flannel, I had to pour the beef broth into sterilized Petri dishes and let it set along the bottom. Then I could inoculate each plate with dust from my home and other common vectors to estimate their concentrations of dirt, germs, and disease.

I encountered unexpected problems with the reconstruction almost immediately. At the grocery store, I debated which cut of beef to use for my culture medium and mistakenly bought pectin instead of gelatin as a coagulant. Pectin, I discovered, helps convert sugars into jams and jellies but does not bind to the proteins of beef broth, and this belated revelation cost me several days of work and my entire first batch of nutrient gelatin. I also had difficulty straining the beef broth for my dust-gardens and had to overcome my relative lack of experience as a cook. Unlike many housewives who practiced household bacteriology during the Progressive Era, I had more familiarity with microbes than domestic labor. 

Middle-aged women living around the turn of the 20th century dealt with the transition from the filth and miasma theories of disease to germ theory, and home economists like Elliott introduced their students to germs with scenarios from their daily lives: “Perhaps you forgot to change the water in a vase of flowers and it stayed there a week. How did it smell when you poured it out? How did the stems that had been in the dirty water feel?” Household bacteriology combined two different forms of expertise: the embodied knowledge of ordinary women and experimental science.

Once I successfully prepared my nutrient gelatin, I inoculated 13 dust-gardens with contaminants including airborne dust from my dining room, my index finger, my cat Ludwig, a one-dollar bill, dead insects, and a ballpoint pen. I exposed my cultures to different amounts of light, heat, and moisture to assess how environmental conditions and specific vectors affected their growth. Despite my low expectations for these experiments, every one of my dust-gardens produced visible colonies within the first week. 

Elliott herself explained how these microorganisms would gradually multiply from “minute light-colored specks” on the plate into pink, yellow, orange, green, blue, and red “spots” with textures like moss, seaweed, or even velvet. The similarity between my results and those from the textbook not only confirmed the viability of household bacteriology but also illustrated how ordinary wives and mothers used dust-gardens to quantitatively assess their sanitary routines. These kitchen tests pulled together gardening, microbiology, and the seed-and-soil model of disease, which theorized that patients fell ill when germs settled and ultimately reproduced inside the tissues of their hosts. Culturing yeasts, molds, and bacteria resembled tending delicate plants, but eradicating disease from the home involved destroying them like weeds.

Experimental “dust-gardens” two weeks after preparation | Personal photograph from the author

As the reconstruction continued into its second week, however, the methodological and intellectual constraints of household bacteriology became increasingly obvious. Although I kept my plates inside an air-conditioned room throughout the experiment, my makeshift beef gelatin quickly melted and transformed my solid cultures into films on a liquified medium. Even if the women who studied household bacteriology had access to a laboratory-grade microscope, they would have found it nearly impossible to isolate individual colonies from their dust-gardens for further analysis. 

According to Elliott, the ability to correctly identify microorganisms “makes no difference” to the typical housewife, and this assumption shaped what knowledge students could and could not learn from tests designed primarily to count microbes. Dust-gardens adhered to a single principle: dust enabled germs to survive and replicate outside of the body, and more dust meant more pathogens and higher probabilities of infection. Detecting specific microbes, on the other hand, caused material difficulties for kitchen experimenters.

Despite these limitations, household bacteriology clearly resonated with Progressive Era homemakers. Interested women produced and exchanged photographs of their own dust-gardens and discussed how their results informed their day-to-day housework and their sanitary activism beyond the home. If every wife and mother learned the principles of microbiology and domestic hygiene from the American School of Home Economics, a satisfied graduate named Mrs. W. H. Eldredge declared, “it would do much more towards stamping out disease and do more towards educating and uplifting humanity than all the hospitals and all the public libraries that have ever been given for that purpose.”


Decades before the appearance of penicillin and other antibiotics, dust-gardens offered a cheap, practical, and reliable means to detect and control disease. For the middle-aged woman who considered science essential to the home but had few opportunities for adult education, household bacteriology drew together the laboratory, classroom, and kitchen to make germs central to daily life. As another student referred to as “Miss G.” elaborated, “such knowledge is rapidly creeping into schools and colleges, but too late for us—and we don’t want to be left behind by school-girls.” 

Historical reconstructions promise more than firsthand knowledge of the procedures and results of pedagogical experiments; they encourage us to analyze the material history of science education and to make our courses more interactive. Historians often emphasize the curriculum, theory, and administration of science classes over the day-to-day experiences of instructors and students. Replicating the equipment and activities of household bacteriology and other practical fields helps correct this imbalance and narrows the distance between us and people of the past. 

Just as household bacteriologists used kitchen experiments to instruct ordinary Americans about germs, so too can we reproduce these experiments to let students discover the complexities of turn-of-the-century germ theory for themselves.

Further Reading

Peter Heering and Roland Wittje, eds., Learning by Doing: Experiments and Instruments in the History of Science Teaching (Stuttgart: Franz Steiner Verlag, 2011).

Suellen Hoy, Chasing Dirt: The American Pursuit of Cleanliness (New York: Oxford University Press, 1995).

Nancy Tomes, The Gospel of Germs: Men, Women, and the Microbe in American Life (Cambridge: Harvard University Press, 1998).

Alexander Parry is a PhD student at the Johns Hopkins History of Medicine Department, researching how domestic accidents shaped housework, consumption, and the home over the course of the 20th century. Contact him at or on Twitter @AlexParryHSTM.

Image credit: Selected Dust-Gardens from Household Bacteriology, 1907 (S. Maria Elliott, Household Bacteriology (Chicago: American School of Home Economics, 1914) 99, 101, and 103 | Public Domain)

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