This was from 2009 in the QJM: An International Journal of Medicine, but I just came across it:
Did Darwin read Mendel?
David Galton
Read no further if you want a definite answer to this question. It is a sort of detective story with clues scattered around. The circumstances surrounding the question however are so interesting since they involve two of the most important scientific publications of the 19th century.
Read the rest here.
The Dispersal of Darwin 
Thanks for posting this. How fascinating that Darwin read Hermann Hoffman’s work and made notations on either side of the reference to Mendel. It seems he came so tantalizingly close to recognizing Mendel’s work, far closer than I realised.
It’s perhaps the bitterest of scientific ironies that Darwin and Mendel were contemporaries but never corresponded. I don’t know that too much can be read into Darwin’s comment to Romanes. I couldn’t find the whole letter, but I suspect Darwin would have gladly been proven wrong and would have loved to learn of Mendel’s discovery.
Welcome!