A whole new sphere of science is being opened up. Homunculus has been created without the help of so much as Faust's retort! The surgeon's scalpel has called into being a new human entity. Professor Preobrazhensky, you are a creator.

Mikhail Bulgakov, The Heart of a Dog

Demikhov was successful, in a somewhat attenuated sense, of transplanting the heads of dogs. I'll return to what that actually means and why we don't today have the ability to transplant human heads, but there's a particularly Russian underpinning to the imaginative biosciences of the Soviet Union.

The aspirations of biomedical rejuvenation, immortality, and transplantation are deeply embedded in a utopian, Bolshevik vision. And why not? The Bolsheviks had succeeded in claiming their new state, and on that vast, unknown horizon, anything may be possible. Key Bolshevik leaders supported imaginative biomedical sciences: Alexander Bogdanov, for example, gave blood transfusions to Lenin's sister Maria, before dying at the age of 54 due to...bad blood transfusions. But the foundation of radical experimentation develops in the earliest Soviet Union. Alexander Beliaev's Professor Dowell's Head is a more straightforward science fiction novella exploring exactly this idea, of transplanting heads; here the scientific figures, like Preobrazhensky, draw out the ethical considerations as well as the hopes (and there's a pretty fun late Soviet film adaptation).

The passage from Heart of a Dog highlights both the utopian conception of scientific progress while sharply critiquing the Soviet Union (Preobrazhensky lives in a large and grand apartment by himself as he treats the high-ranking functionaries of the party - and one of the first words our transformed stray dog utters is bourgeois). But Bulgakov continues, raising several rather intriguing and challenging questions as to the place of humanity:

In my opinion, we are dealing with a revived and developing, not with a newly-created brain. Oh, what a divine confirmation of the theory of evolution! Oh, great chain of life from a stray dog to Mendeleev the chemist! Another hypothesis: Sharik's brain, during his period as a dog, collected a mass of information. All the words with which he first began to operate are street words, he had heard them and they had been conserved in his mind. Now as I walk along the street I look with secret horror upon every dog I meet. God knows what is stored away in their brains.

Recall Darwinism receives widespread acceptance only in the 1870s, and that Russian evolutionists are in general rather conservative even then (largely subscribing to a form of evolution that centers less competition). So in fifty years incredible scientific progress has happened, which contributes in part to the vision of constructing a New Soviet Man, a recurrent and complicated archetype. Mayakovsky's Bedbug satirizes the efforts to reshape Soviet society that fall along the same goals to conquer death. Psychology and psychiatry for the Bolsheviks are squarely modern sciences, though they devolve into the 1930s after the Cultural Revolution, and the prospect of elevating humanity and even conquering biology was possible, imminent, and important.

Demikhov was active as early as the 1930s, where he purportedly implanted an artificial heart into a dog, but chiefly worked in the 1950s and 1960s. (As a brief aside, rudimentary head transplant experimentation occurred as early as 1908 by Charles Guthrie and Alexis Carrel). The photos you'll find online are authentic; Demikhov did succeed in transplanting heads and registering responses, though all animals died within days and most within hours. One dog lived for over four weeks, which is really quite remarkable!

In the 1970s Robert White successfully performed head transplants on Rhesus monkeys, which furthered Demikhov's research but largely saw the same results, in turn eliciting significant protests. More recently efforts to transplant human heads have been revived but are somewhat outside the scientific communities due to the difficulty and danger. Demikhov never could have been successful because of the quantities of immunosuppressive drugs used (but his techniques for organ transplants were foundational); even White was unable to keep the animals alive for particularly long, and the rather apparent cruelty of this experimentation is a hard pill to swallow. Few scientists entertain the possibility of head transplants currently, though some do, and the fictional organ transplants of the 1920s were reality by the 1960s, so who knows what the future holds!