by Adrienne Mayor (Wonders & Marvels contributor)
One of the most feared poisons in classical antiquity was obtained from the so-called Purple Snake. According to the Roman natural historian Aelian (ca AD 200), this snake from the “hottest regions” of Asia had deep purple body and a head “as white as milk.” It was described “almost tame” and unable to strike with fangs. But if this reptile were to vomit on your leg? The entire limb putrefies and you die, quickly or “little by little.”
Aelian’s Purple Snake had never been identified. Curious, I contacted a herpetologist. He was struck by two details in Aelian’s description: the remarkable white head and the habitat in the “hottest part of Asia.” Aelian’s information must have come to Rome from travelers on the Silk Route. The Purple Snake matches the description of a rare, white-headed viper of China, Myanmar, and Vietnam, unknown to science until 1888. Azemiops feae is the only tropical Asian venomous snake with a distinctive white head. The body, dark blue-black with red bands, appears purple especially when the scales reflect light or if a preserved specimen is observed. A primitive viper with short fangs and small venom sacs, Azemiops is described by herpetologists as “docile but dangerous.”
According to Aelian, collecting the toxins of the Purple Snake for making poison was complex. To extract the venom, you suspend the live viper alive, head down over a bronze pot to catch the dripping poison, which congeals and sets into a thick amber-colored substance. When the snake eventually dies, replace the first pot with another to catch the watery serum flowing from the carcass. After three days, this foul liquid jells into a deep black substance.
These two poisons of the Purple Snake should be kept separate, as they kill in different ways, both dreadful. The black poison causes a lingering, wasting death over years from spreading necrosis and suppurating wounds. The pure amber venom causes violent convulsions. Then, declares Aelian, the victim’s “brain dissolves and drips out his nostrils and he dies a most pitiable death.”
Feeling queasy? That reaction was exactly the intention of poison arrow makers in antiquity. Simply dipping arrows in the pure venom would be deadly enough. Dried crystallized venom can retain neurotoxicity, and the rotting vipers’ body contributed bacterial contaminants to wreak havoc in a puncture wound. The very idea of an enemy supplied with Purple Snake poison was terrifying. And indeed, broadcasting your ghastly poison recipes to potential enemies was an important psychological aspect of biological warfare.
The disastrous result of “vomiting” on a victim described by Aelian probably referred to venom that accidentally dripped into an open sore. Azemiops venom has not been fully analyzed, but it is a hemotoxin with devastating effects and significant necrosis. Notably, in 2012, chemists isolated a novel polypeptide, Azemiopsin, by gel filtration of the venom residues, which they hope may be valuable in neurotransmitter research and biomedical applications.
About the author: Adrienne Mayor is a Research Scholar in Classics and History of Science, Stanford University. She is the author of “Greek Fire, Poison Arrows, & Scorpion Bombs: Biological and Chemical Warfare in the Ancient World” (2009); and “The Poison King: The Life and Legend of Mithradates, Rome’s Deadliest Enemy,” a nonfiction finalist for the 2009 National Book Award.