by John Aitken

Parents of children sometimes get strange requests for birthday or festive presents. My obsession at the age of ten was to have a microscope. (I wanted to look at a fly’s eye!) Eventually my parents gave in, and soon the little Japanese tin microscope was on my bedside table. I spent many happy hours using it. Even today, one of my questions to prospective job candidates is: “Did your parents ever give you a microscope as a present when you were a kid?”

In the late 1800’s Robert Koch, a family doctor in Germany, bought himself a microscope. He quickly became immersed in the hobby of studying the microscopic world and became proficient in the use of the instrument, aided by a laboratory he had built on the side of his physician’s office. By 1878 he had discovered the bacterial cause of anthrax. This resulted in his appointment to the Imperial Health Bureau in Berlin in 1880, where he had access to a new laboratory.

Koch extended his studies further into the unknown, which was a relatively large field in the 1880’s! The great mystery at that time was the disease consumption, now know as tuberculosis (TB). Tuberculosis was, and still is, a killer disease, yet the agent causing the disease was completely unknown. There were many theories as to why patients contracted TB, which was often a death sentence. The theories ranged from overcrowding and poor food, to lack of sunlight and fresh air.

When TB was viewed under a microscope, the changes seen by pathologists were well described. The appearance of infected tuberculous tissue was not unlike that seen today in samples from patients with Crohn’s disease. At this time, the German dye industry was in full swing, and new stains were available to researchers to aid in the differentiation of tissues seen under the microscope. Tissue sections from the lungs of TB patients appeared as if the body was fighting an infection, but no bacteria could be seen. A similar disease to human TB could be seen in cattle, but again, no organisms could be seen. (Does any of this sound familiar to modern day Crohn’s patients?!) Using the new stains, and a taxing period of trial and error, Koch eventually struck oil. He was able to distinguish a small bacillus seen in the tissue of TB patients, but not in the tissue of normal samples. Moving ahead, he then successfully grew the organism on agar plates, another of his discoveries, and injected it into guinea pigs, thus demonstrating the lethal potential of his discovery.

Koch’s former status as a general practitioner did not endear him to his colleagues in the newly developed field of bacteriology, so the crucial presentation of his work took place on the 24th of March 1882 at the Berlin Psychological Society.

Koch knew his audience well. Prior to his presentation, he had set up a mini-laboratory in the lecture hall to demonstrate the entire process and demonstrate the organism under the microscopes available at the time. The lecture must have been an astonishing experience for those who had denied the “germ theory” of tuberculosis. I wish I could have been there myself. Starting hesitantly and quietly, Koch laid out the steps he had covered to confirm his discovery. At the end of his lecture there was no applause, no questions, and no comments. The listeners were struck dumb. Slowly, the audience members rose from their seats and went to the front of the lecture hall to peer down the microscopes and see for themselves.  As Koch well knew, “Seeing is believing.” Thus, the discovery of Mycobacterium tuberculosis was announced to the world.

Koch had planned his work meticulously.  He had framed his investigation along four important principles, known now as Koch’s postulates.

1. Identify a specific organism.
2. Obtain a pure culture of that organism.
3. Reproduce the disease in experimental animals using the pure culture.
4. Recover the organism from the infected animals.

By following rational and scientific methodology in 1882, Koch was able to make the first move towards ridding the world of a great pestilence.

So to all the parents out there: Listen carefully to the birthday presents requested by your children. Among the standard requests for X Boxes, iPhones and other electronic devices, there are some children who just want a microscope. That kid will be the scientist of the future.  Give them a microscope, and big hug from me.