I’d never heard of this before: just to be sure, I checked Reuben Ogburn’s 2004 page on “Writing in and around plant illustrations” in case it had slipped in there, but no sign. If you run this through Jon Grove’s colour separator filter, you can see that the brown ink used for the drawing and the brown paint used to fill it in are very slightly different: in the image below, the white area is where the filter thinks the overpainting happened.
But is there writing beneath? If you squint at the topmost image here long enough, you can start to make out something that might almost be writing. But if you filter it slightly differently, I think the answer emerges: the “signal” (below) appears to be not writing, but only compression artefacts from the MrSID wavelet encoding. Sorry, guys: false alarm! (Though next time I’m at the Beinecke, I’ll have another quick look, just to be completely sure…)
