Is the ‘Darwin-Marx correspondence' authentic?

For many years there has been a good deal of scholarly and ideological writing on the correspondence which is said to have taken place between Karl Marx and Charles Darwin. The two presumed letters from Charles Darwin to Karl Marx have been published several times, and their significance appraised. In this article their authenticity as letters to Marx is discussed and questioned, and the possibility that Edward Aveling is the addressee of at least one of them is argued.