My colleague, Maxine, says that Kunstformen der Natur means Artforms of Nature. It is an online scan of a beautiful book, a collection of page plates of living things, many microscopic, but in any case, beautiful shapes that have been rendered in drawings by Ernst Haeckel. These images are pretty spectacular - some in color and others black & white. If anyone knows more about this book, or Ernst Haeckel, I'd be interested to hear about it.
I think the whole book can be downloaded from this site also, though my German is non-existent, so I'm not certain!