|“||'During my time of trial, these last few weeks, I have read all sorts of things. Among others, Darwin's book of Natural Selection. Although it is developed in the crude English style, this is the book which contains the basis in natural history for our view'.||”|
Also written in the book "Evolution, Marxian Biology, and the Social Scene", Marx wanted to dedicate Das Kapital to Darwin. In the book 'Ever Since Darwin' , a copy of the first volume of Das Kapital is inscribed by Marx--describing himself as a "sincere admirer" of the English naturalist. 
- Conway Zirkle, Evolution, Marxian Biology, and the Social Scene (Philadelphia: University of Pennsylvania Press, 1959), pp. 85-87
- Stephen Jay Gould, Ever Since Darwin (New York: W. W. Norton and Co., Inc., 1977), p. 26.