Fast-forward to the 1800s, where 2 German scientists discovered something that today we might find rather obvious, but helped tie together what we now know as the cell theory.
The first scientist was Matthias Schleiden, a botanist who liked to study plants under a microscope. From his years of studying different plant species, it finally dawned on him that every single plant he had looked at __________. At the same time, on the other end of Germany was Theodor Schwann, a scientist who not only studied slides of animal cells under the microscope and got a special type of nerve cell named after him. After studying animal cells for a while, he, too, came to the conclusion that all __________.
Immediately, he reached out via snail mail to other scientists working in the same field with Schleiden, who got back to him, and the 2 started working on the beginnings of the cell theory. A bone of contention arose between them. As for the last part of the cell theory -- that __________ -- Schleiden didn't exactly subscribe to that thought, as he swore cells came from free-cell formation, where they just kind of spontaneously crystallized into existence.
That's when another scientist named __________, stepped in with research showing that cells did come from other cells, research that was actually -- hmm ... How to put it? -- "borrowed without permission" from a Jewish scientist by the name of Robert Remak, which led to 2 more feuding scientists. Thus, from teeth gunk to ticking off Newton, crystallization to Schwann cells, the cell theory came to be an important part of biology today.