This will probably be a hard one to answer, but I'm looking for the name of a story from a book of science fiction short stories about primordial ooze that evolves into humans, into advanced stages,and all the way back to primordial ooze again. I'm not sure when the story (or the book for that matter) was published, but I remember reading it about 11 years ago. I had found the book in a bin of donate books, so I know the book is an older book.I thought it was maybe an Isaac Asimov story because of the twist at the end , but through my research I don't think it is. Sorry for the crude description. Thanks!
It is quite old (1931) and featured in one of Asimov's anthologies.
It has a feeling--to me--of B-series horror movie (including most of the "science" explained).
Two friends visit the archetypical mad, isolated scientist. He explains that evolution (from primordial ooze up to mankind) is caused by cosmic radiation and that he has created a device that concentrates the radiation received over a large area, and focuses it on him (so he would "evolve" faster). He puts the machine to use several times in a row, each time his brain is getting bigger and bigger while his body declines.
IIRC, after the second time he declares that he will become master of the world, at the next step (barely a brain with vestigial organs) he has further evolved and tells he is no longer interested in such puny things as world conquest, and after the next and last, it is found that he has devolved to the primordial ooze).
In the end, the shock of the discovery causes one of the original friends to become crazy, a (convenient) fire destroys the mad scientist's lab, and the remaining friend is the narrator.
The ooze appears as the beginning of the evolution (but only mentioned, the test subject is the mad scientist from the start) and as the final result.
More on this: https://en.wikipedia.org/wiki/The_Man_Who_Evolved