Fact Check

Urine Test

Professor demonstrates diabetes test by dipping his finger in flask of urine and licking it.

Published Jul 1, 2011

Claim:   A medical school instructor lectures the class on the importance of taste as a diagnostic tool and demonstrates his point by conducting a diabetes test which involves dipping his finger into a flask of urine and licking it.



[Grenfell, 1932]

A Glasgow teacher, in order to emphasize the value of observation, prepared a little cupful of kerosene, mustard and castor oil and, calling attention of his class to it, dipped a finger into the atrocious compound and then sucked his finger. He next passed the mixture around to the students, who did the same with dire results. When the cup returned and he observed the faces of his students, he remarked: "Gentlemen, I am afraid you did not use your powers of observation. The finger that I put into the cup was not the same one that I stuck into my mouth."

[Collected on the Internet, 1999]

The consultant urologist is demonstrating urine sampling to a class of students. As each sample is passed to him, he dips a finger in the bottle, raises his hand to his mouth and licks it. the standard tests follow and
after each one he mutters "Hmm, thought so, too high/low a sugar level", etc.

The students were then invited to follow his example, which they duly did, including the finger dipping and licking.

At the end of the class, the consultant addressed the students. "While I cannot fault you on your general techniques", he said, "I would recommend that you pay more attention to observation". He continued, "If you had been more alert, you would have realised that, when I dipped my finger in the sample prior to testing it, I then licked a different digit — class dismissed".

[Collected via e-mail, August 2009]

First-year students at the UC Davis Vet school were receiving their first anatomy class, with a real dead cow.

They all gathered around the surgery table with the body covered with a white sheet. The professor started the class by telling them, "In Veterinary Medicine it is necessary to have two important qualities as a doctor: The first is that you not be disgusted by anything involving the animal body." For an example, the Professor pulled back the sheet, stuck his finger in the anus of the dead cow, withdrew it and stuck his finger in his mouth.

"Go ahead and do the same thing," he told his students. The students freaked out, hesitated for several minutes, but eventually took turns sticking a finger in the anal opening of the dead cow and sucking on it.

When everyone finished, the Professor looked at them and said, "The second most important quality is observation. I stuck in my middle finger and sucked on my index finger. Now learn to pay attention. Life's tough, it's even tougher if you're stupid."



  • One variant of this legend involves an instructor who inserts one gloved finger up a patient's rectum and then licks a different one.
  • This story is also told about public school science teachers who use a foul-tasting substance (such as a weak acid) to demonstrate the merits of careful observation to their students.

Origins:   This


legend is an old medical school tale dating to at least the 1930s, and it has also appeared in a number of recent works. (See the "Sightings" section below.)

The origination of this story has often been attributed to Dr. Joseph Bell, the Edinburgh University instructor on whom Sir Arthur Conan Doyle modeled the character Sherlock Holmes. An article (date and origin unknown) by Dr. Harold Emery Jones, a classmate of Doyle's at Edinburgh Royal University, recounts the now-familiar legend:

Bell was as full of dry humor and satire, and he was as jealous of his reputation, as the detective Sherlock Holmes ever thought of being.

One day, in the lecture theatre, he gave the students a long talk on the necessity for the members of the medical profession cultivating their senses — sight, smell, taste, and hearing. Before him on a table stood a large tumbler filled with a dark, amber-colored liquid.


gentleman," announced the Professor, "contains a very potent drug. To the taste it is intensely bitter. It is most offensive to the sense of smell. Yet, as far as the sense of sight is concerned — that is, in color — it is no different from dozens of other liquids.

"Now I want to see how many of you gentlemen have educated your powers of perception. Of course, we might easily analyze this chemically, and find out what it is. But I want you to test it by smell and taste; and, as I don't ask anything of my students which I wouldn't be willing to do myself, I will taste it before passing it round."

Here he dipped his finger in the liquid, and placed it in his mouth. The tumbler was passed round. With wry and sour faces the students followed the Professor's lead. One after another tasted the vile decoction; varied and amusing were the grimaces made. The tumbler, having gone the round, was returned to the Professor.

"Gentlemen," said he, with a laugh. "I am deeply grieved to find that not one of you has developed this power of perception, which I so often speak about; for if you had watched me closely, you would have found that, while I placed my forefinger in the medicine, it was the middle finger which found its way into my mouth."

These methods of Bell impressed Doyle greatly at the time. The impression made was a lasting one.

Sightings:   Versions of this legend appear in Richard Gordon's series of Doctor books, the film spoof Young Doctors in Love, and the first episode of the ten-part BBC television series Doctors to Be.

Last updated:   30 June 2011


    Brunvand, Jan Harold.   Too Good To Be True.

    New York: W. W. Norton, 1999.   ISBN 0-393-04734-2   (p. 430).

    Grenfell, Wilfred.   Forty Years to Labrador.

    New York: Houghton Mifflin, 1932.

    Healey, Phil and Rick Glanvill.   Now! That's What I Call Urban Myths.

    London: Virgin Books, 1996.   ISBN 0-86369-969-3   (pp. 189-191).

    Kaye, Mavin.   The Game Is Afoot.

    New York: St. Martin's Press, 1994.   ISBN 0-312-10468-5   (p. 27).

    The New Anecdota Americana.

    New York: Grayson Publishing Corp., 1944   (p. 53).

David Mikkelson founded the site now known as snopes.com back in 1994.

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