Courtesy of the British Library

German prospector Erich von Mülrisch arrived in Brazil in 1899, with the express purpose of finding rubber groves to harvest. He had already amassed a workforce in the city of Salvador, and after serving years in the Prussian cavalry, he was determined to make his fortune in South America.

If anyone could take advantage of Brazil’s bounty, it was Mülrisch. He had proven himself a ruthless fighter during the Franco-Prussian War, and it was rumored he ordered the deaths of unarmed French prisoners by firing squad. He had also taken a degree in civil engineering and was versed in botany. He had bribed the proper officials in the state of Bahia, and locals whispered of his impending takeover.

One day, while roaming a forest in the municipality of Paranatinga, his Indian guide led Mülrisch to an enormous tree.

“I measured its circumference to 46 meters,” wrote Mülrisch in his journal. “I wonder if any tree in Europe has ever measured such girth. The surface of the tree was soft and strange, as if speckled with a kind of glitter.”

His guide also pointed to a place where the bark had been worn away, and on the denuded surface was carved a series of petroglyphs.

“My native footman took great interest in these glyphs,” wrote Mülrisch. “He pronounced the words each symbol represented, and I took pains to repeat them back to him. It is a savage language, and its sounds are unsuitable for civilized tongues, but my man seemed satisfied with my imitations.”

That night, Mülrisch dreamt that he was being squeezed to death in a nest of sentient branches. He awoke in a cold sweat, and he realized that he had contracted fever. Then he noticed small bumps underneath his skin. In a few days, these welts became pronounced and painful. He begged a doctor to examine them, but the doctor insisted that they were too hard to lance. At last they attempted a biopsy, and they were shocked to discover that each “bump” appeared to be a large acorn, which had mysteriously grown underneath Mülrisch’s skin.

The acorns seemed to take root inside his body, and protrusions (which looked like young branches) began to push through his skin. This caused him extraordinary pain, and Mülrisch decided to flee Brazil in search of more familiar physicians. During his passage across the Atlantic, the “buds” turned black and brittle, and finally they fell away. By the time he reached the port of Hamburg, the swelling had gone down, and the hardness had dissolved.

The incident was not without long-term effects: His arms remained perforated for the rest of his days, and Mülrisch became a recluse. He ordered all the trees around his country home cut down, and he eventually locked himself in his bedroom, where he ate only meat and cheese. After three years without human contact, Mülrisch failed to signal to his caregivers (three knocks on the door), and he was found dead, most likely from scurvy.