> Stoker, a theatre manager with no medical background, somehow described the basic mechanism of heterochronic parabiosis

Just to pick a nit...

Stoker's story was inspired by "The Vampyre" by physician John Polidori, who doubtless knew whatever his contemporary medics knew about blood.

Polidori, Lord Byron, and Mary Shelley told scary stories to each other by Lake Geneva in 1816, the "year without a summer". It couldn't get more gothic.

https://publicdomainreview.org/essay/the-poet-the-physician-...