The combination of green and black make me think of "The Shrinking of Treehorn." Now that is one delightfully off-kilter kid's book.
In light of the fact that these had been a bookworm's smorgasbord (literally - you can see the pages they chomped on), this encyclopedia is headed for greener pastures. I cut out some pages for use in my own projects, and realized, several volumes later, there is no way I will humanly ever use this many images of single cell life-forms. In light of the fact, I've been making up packs of these for Etsy where I can hopefully reduce the embarrassingly large quantity of paper ephemera surrounding me.