Over 40 years ago I started working on blood cell counters. This was one of my earliest - Coulter Counter Fn. (FYI -I continue to work on another analyzer leading the world in blood cell counters - Sysmex)
Truly groundbreaking and innovative at the time, but as I look back I recall these tubes that would spin around as it counted blood cells. I know later versions (ZBI) had nixi-tubes, but don't know what to call these.....

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The most exciting phrase to hear in science, the one that heralds new discoveries, is not "Eureka" but rather "Hmmmmm...that's funny" - Isaac Asimov 1920-1992
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