Conn, _Biology_. Silver, Burdett & Co.
Darwin, _Life and Letters of Charles Darwin_. Appletons.
Galton, _Hereditary Genius_. London (1892).
Thompson, _Heredity_. John Murray, London England.
Wasmann, _Problem of Evolution_. Kegan Paul, Trench, Truebner and Co.,
London, E. C.