I recently discovered Ernst Heackel's amazing scientific drawings. I
have long been a fan of botanical/scientific drawings but hadn't heard of Heackel. Now I have to get my hands on his book, Art Forms in Nature. Yikes. All of the above images are from that book, I believe. I ran into his name while working on a science lesson plan for one of my classes. He is the author of the term," Ontogeny Recapitulates Phylogeny. Which informed much of our beliefs about evolution but not in the literal sense that he intended it. Basically it's modern iteration is that many developments take place during ontogeny (a species' development) that repeat or parallel it's species evolutionary development
( phylogeny). Okay I am no scientist. That is my wild stab at understanding this... Anyway, his artwork is gorgeous.