When I first found Santiago Ramón y Cajal’s drawings of neurons and cells I was fascinated just how aesthetically pleasing they looked. Totally different from many drawings in textbooks.
The Cajal Institute also has some more of his drawings.
pay-walled
edit: Just installed this add-on in Firefox and it works perfectly to get past most paywalls including this one. Link: https://gitlab.com/magnolia1234/bypass-paywalls-firefox-clean
Here is a link to the page with the file if you cant find it in the installation instructions on the other page. Link: https://gitlab.com/magnolia1234/bypass-paywalls-firefox-clean/-/releases
Just download the .xpi file then drag it onto any tab/page in Firefox and it will prompt you to add it. It’s all explained in the instructions on those two pages. I’ve been looking for something like this for a while I’m glad it works so well. good luck!