A page from Isaac Newton's notebook, with a sketch of an experiment where he stuck a needle into his eye socket. Cambridge University Library

How many scientists are willing to take a dose of their own medicine -- or go under their own knife? Surprisingly more than you might think. Self-experimentation, it turns out, is a grand tradition in science.

In a recent piece for Wired, science writer Deborah Blum tells the tale of Jonathan D. Allen, an invertebrate biologist at the College of William and Mary. Allen recently published a paper in the American Journal of Tropical Medicine and Hygiene on a rare case of infection by the nematode parasite Gongylonema pulchrum. The patient? Jonathan D. Allen.

Allen was 36 and healthy when he began feeling “a rough patch in his mouth, a scaly little area [in] his right cheek,” Blum writes. “It didn’t hurt. But then it didn’t stay there either. He started testing for it with his tongue. It traveled. It moved to the back of his mouth, then forward, coiled backwards again.”

Despite Allen’s description -- and pictures -- of a strange something living in his mouth, an oral surgeon disputed his story. One night, Allen felt the thing moving again and, with the help of his wife, extracted a tiny worm-like parasite, which he confirmed to be a specimen of G. pulchrum with some genetic analysis help from a colleague at Eastern Virginia Medical School. Allen’s the 13th known case of Gongylonema infection in the U.S., and one of about 50 cases identified worldwide.

It takes a bold researcher to remove his own parasite; it takes an even bolder one to put it in there in the first place. Perhaps the most famous and well-rewarded example of self-infection is that of Australian physician Barry Marshall.

Marshall was investigating the link between the bacteria Helicobacter pylori and ulcers; in the course of his research, he drank a petri dish full of H. pylori and developed gastric inflammation, bad breath and nausea. Cultures taken from his guts showed H. pylori had bred, proving that the microorganism was infectious and disease-causing. For this and other work that proved H. pylori, not stress, was the primary cause of stomach ulcers, Marshall shared the 2005 Nobel Prize in Physiology or Medicine.

Throughout medical history, many advancements have found their early subjects in the experimenters themselves. Karl Landsteiner discovered blood groups thanks to samples from himself and his laboratory staff. German physician Werner Forssmann put himself under local anesthesia and threaded a catheter through a vein in his arm and into his own heart -- the procedure had not been attempted before.

Isaac Newton was especially hard on himself with his own experiments. The young physicist once stuck a flattened needle, or bodkin, between his eyeball and eye socket and moved it around, deforming the shape of his eye to see what effect it had on his vision. In his diary, Newton remarked on the various colored circles that he saw when he moved the bodkin around.

Newton’s interest in vision and light also drove him to stare at the reflection of the sun in a mirror. The bold scientist was blinded for about three days and saw afterimages of the sun for months afterward.

Without such bold -- or perhaps foolhardy -- self-experimenters, we might not know as much about medicine or physics as we do today. But if you’re a budding scientist yourself, keep in mind that there are plenty of researchers that have found success and discovered great things without poisoning, infecting or blinding themselves.