Sunday, August 03, 2014

Microbe Hunters by Paul de Kruif

Microbe Hunters’, as I have often been told, is a classic reading in microbiology—one of those books that can inspire the beginning of a career. In this book, written in 1926, American microbiologist and author Paul de Kruif proposes to acquaint us with the great pioneers of microbiology, from Leeuwenhoek to Ehrlich, via Pasteur, Koch, Roux and several more. 

I gave it a try, and I must confess that at first I was a bit taken aback by the quite unusual style of the author: extremely enthusiastic, overly lyric, made to immerge us in the life of the protagonists with a plethora of details that may or may not be true.  I can’t remember reading anything quite approaching the surprising and unusual tone of Microbe Hunters. Here’s an example describing Spallanzani’s early experiments (p. 34):

“What’s this?” [Spallanzani] cried. Here and there in the gray field of his lens he made out an animalcule playing and sporting about—these weren’t large microbes, like some he had seen—but they were living little animals just the same.
“Why, they look like little fishes, tiny as ants,” he muttered—and then something dawned on him— “These flasks were sealed- nothing could get into them from the outside, yet here are little beings that have stood a heat of boiling water for several minutes!”
[…] It was a great day for Spallanzani, and though he did not know it, a great day for the world.

But as I was reading further I grew accustomed to this prose, and, to my own surprise, I started to enjoy it! It is indeed difficult not to share de Kruif’s enthusiasm for these great men of the past and, even though I would take the author’s factual accuracy with more than a grain of salt, the book really makes you want to learn more about the personal life of these pioneers.

Notably, the figures of Pasteur and Koch are vividly brought to us, and the comparison of the two is striking (p.147-148):

Nothing is truer than that there is no one orthodox way of hunting microbes, and the differences between the ways Koch and Pasteur went at their work are the best illustrations of this. Koch was as coldly logical as a text-book of geometry—he searched out his bacillus of tuberculosis with systematic experiments, and he thought of all the objections that doubters might make before such doubters knew that there was anything to have doubts about. Koch always recited his failures with just as much and no more enthusiasm than he did his triumphs. There was something inhumanly just and right about him and he looked at his own discoveries as if they had been those of another man of whom he was a little over-critical. But Pasteur! This man was a passionate groper whose head was incessantly inventing right theories and wrong guesses—shooting them out like a display of village fireworks going off bewilderingly by accident.
The great Pasteur, one of the "microbe hunters"(Wikimedia Commons)

De Kruif does a great job at describing the great endeavors accomplished by these men, who were motivated both by scientific curiosity and by societal necessity: in the 19th century, the toll paid by the human race to contagious diseases was enormous. Because, in important aspects, the story of microbiologists is the story of hunting diseases: anthrax, transmitted by the spores of the bacterium Bacillus anthracis (Koch identified the germ, and Pasteur developed the first vaccine in 1881); rabies, the viral disease also fought by Pasteur; diphtheria, caused by a bacterial toxin; Texas fever, due to a Protozoan that infects cattle via a tick; the sleeping sickness, a Trypanosoma transmitted to humans via the tsetse fly; and malaria, of course, caused by another Protozoan transmitted by a mosquito. 

De Kruif is optimistic (and enthusiastic!) about the power of men of science to fight infectious diseases and thus alleviate the sufferings of mankind. It is worth noting that Microbe Hunters was published two years before what would become the greatest discovery of all times: the discovery of penicillin by Fleming.

I would recommend Microbe Hunters, as long as one accepts its exuberance (or maybe because of it!).


  • De Kruif, Paul. (1926) Microbe Hunters. Blue Ribbon Books, New York. 365 pages.


  1. I started reading this book last week on your recommendation. 2015 has just started but I already feel like it's going to break the top 5 of books I've read this year. Brilliant stuff.

    The writing style is GREAT! It's not dry and detached like a lot of academic writing usually is. The Metchmikoff chapter for instance had me laughing out loud multiple times:

    "Almost at once Roux and Metchnikoff made an important find; their experiments were ingenious and they had about them a certain tautness and clearness that was strangely un-Metchnikoffian."

    "To one of these, the science of old age, he gave the sonorous name "Gerontology" and he gave the name "Thanatology" to the science of death. What awful sciences they were; ... the observations he made in them were so inaccurate that old Leeuwenhoek would have turned over in his grave had he known about them; the experiments Metchnikoff made, to support these sciences, would have caused Pasteur to foam with indignation that he had ever welcomed this outlandish Russian to his laboratory ... "

    By the way, if you had to give an estimate, how much of what's in the book would you say is fact and how much would you say is fiction. The book gives insight into how some of the famous microbiologists worked, but I am not sure what to believe and what to throw out. I wish he had provided references or something.

  2. Hi,
    Glad you liked the book! It is indeed quite something. Regarding its accuracy, I wouldn't dare to give an estimate on fact vs. fiction, but we can assume I guess that the reported thoughts of the protagonists are pure inventions. An interesting abstract here (unfortunately the whole article is not available) about this:

  3. Oh thank you! Interesting that Ross sued De Kruif. Controversial, but nevertheless, a very fun book to read. Nowadays it would be impossible for a writer to get away with the inflammatory remarks De Kruif ventured to write in his book.