Koch soon published his work on anthrax, and in a pulse of experiments
and publications over the next several years, demonstrated the presence of
bacteria in wounds, thus supporting the concept of Listerism in surgical
science. He would continue to refine culture techniques, both in Wöllstein
and later Berlin, that are used every day in every hospital and every lab in
the world, including the use of agar as a culture medium and the use of
round glass plates with side walls, named after his assistant, Julius Petri
(the “Petri dish”). Koch worked with the Zeiss company to improve
microscopes and with Leica to invent photomicrography, mammoth
achievements themselves.
Koch’s apotheosis came on March 24, 1882. After establishing himself
as one of the great young innovators in all of Europe, the thirty-eight-year-
old announced he was giving a talk entitled “On Tuberculosis.” Even
though the previous decade had seen the fortification of the germ theory,
agreement on the origin of tuberculosis (TB) was not yet consistent, even
among medicine’s greatest geniuses, including Rudolf Virchow. Rumors
about the gravity of the lecture had circulated among the cognoscenti in
Berlin; the library at the University of Berlin’s Physiology Institute that
Friday night was packed in anticipation of Koch’s demonstration.
Koch started by reviewing the statistics of TB in the 19th century: one
in seven of all human beings died from tuberculosis, but, “If one only
considers the productive middle-age groups, tuberculosis carries away one
third and often more of these.”^39 TB was a true, slow-motion world
pandemic; his erstwhile audience was mired in that reality, but the more he
emphasized its import the more they must have expected a profound
announcement. The trouble was, no one had ever visualized the germ that
caused the disease.
The secret of its covert cold-blooded efficiency was also the
characteristic that made it difficult to image. The tuberculosis bacterium
is now known to be a member of the mycobacterium genus, with over 150
species (including M. leprae, the cause of leprosy) and characterized by a
thick cell wall that is waxy and hydrophobic (not attracted by water). This
thick cell wall helped the small bacillus (from the Latin word for stick,
baculus) hide in a sea of cells, impervious to the typical dyes used to stain
tissues. It was up to Koch and his team to try other chemicals and to alter
conditions to draw out his quarry.