Fascinating. As a one-time biology student and Darwin fan, I had no idea. Thanks for posting.
That really is a fascinating read. In the past I collected a few minor books of similar vintage with an emphasis on collating knowledge, but it never occurred to me that collating colors would be important, particularly to naturalists.
Always find it a bit disappointing that Alexander von Humboldt's influence on Darwin is rarely mentioned. One would think that Andrea Wulff's "The invention of Nature" had changed that