Darwin's 'Origin of Species' revision sheets may sell for 500k

The long-lost revision sheets of Charles Darwin's Origin of Species, that specified corrections for the second edition of the foundational work of evolutionary biology, may fetch up to 500,000 pounds at an auction in the UK.
The fact of these revised sheets has long been known from Darwin's correspondence, but their whereabouts and even survival has remained a mystery to scholars.
The rediscovery of the present annotated copy allows for the first time a precise reading of Darwin's exact revisions without the veil of reconstruction and translation, provides an insight into his working method, and documents the further development of his ideas for his 'big book', according to the Christie's auction house in the UK.

In replying to the proposal to issue a second German edition, Darwin wrote to his German translator H G Bronn, wanting to "make a few more corrections on clean sheets of the last English Edition" and asked for his patience to prepare such sheets.
"I have compared the sheets of the Third English Edition with the Second which was translated into German, & have marked with a pencil line all the additions & corrections," Darwin wrote to Bronn after finishing the work few weeks later.
Darwin's revisions were recently reconstructed by collating the texts of the second German and third English editions and taking into account additions and corrections noted in Darwin's own copy of the third English edition now kept at the Cambridge University Library.

The autograph revisions were sent to his German translator for incorporation into the second German edition. The majority of Darwin's revisions were then incorporated into the fourth English and all subsequent editions, thereby remaining Darwin's definitive text.

The annotated sheets were presumably in Bronn's possession when he died suddenly in 1862.
They were bound up and at some point soon afterwards came to be owned by Darwin's younger contemporary and correspondent, the German palaeontologist, Melchior Neumayr.
In addition to his studies in Munich, Neumayr spent a few years in Heidelberg, first in 1865-66, only three years after Bronn's death, and again in 1872-73 to teach palaeontology in Bronn's former faculty.

The present volume is accompanied by an autograph letter by Darwin to Neumayr, in which Darwin asks Neumayr for his opinion on the work and personal reliability of scientist Leopold Wuertenberger.
Neumayr's positive reply encouraged Darwin to offer financial assistance to Wuertenberger for his work.
While individual leaves of autograph drafts relating to the Origin very occasionally appear on the market, no other example of Darwin's autograph revisions to the text are known to have been offered.