Microscopic protagonists. Hmmm.
I remember a story, but I don't remember the author - it was anthologised with Uncle Tom Cobbley and all : a planetary survey ship crash lands on somewhere fairly nasty, radio smashed, can't call base for whatever McGuffins. They can't get away, so decide to gene engineer human genes into something that can live in the abundant ponds. I can't remember the McGuffin for avoiding the atmosphere. Generations later, the micro-humans are developing a technology and we follow them fighting through the problems of being microscopic, specifically piercing the film of "Surface Tension" separating their watery world from the atmosphere above - which I think was the story's title.
OK, off to Google (well, DuckDuckGo), with an outstanding concern that they'd be over the 1mm cut off. Somewhere they were described in reference to spider size.
Ohhh, well done brain cell! Good hit on
a James Blish story, a literal Hall of Famer. And since the protagonists are clearly described as "microscopic", I'll let my caveat hang in the wind.
Oh, the Internet Archive has the whole number scanned :
https://ia800804.us.archive.org/26/item ... 952_08.pdf