von Dr. F. Rolle. I will not attempt to give references to all the authors
who have taken the same side of the question. Thus G. Canestrini has
published ('Annuario della Soc. d. Nat.,' Modena, 1867, page 81) a very
curious paper on rudimentary characters, as bearing on the origin of man.
Another work has (1869) been published by Dr. Francesco Barrago, bearing in
Italian the title of "Man, made in the image of God, was also made in the
image of the ape."), and especially by Haeckel. This last naturalist,
besides his great work, 'Generelle Morphologie' (1866), has recently (1868,
with a second edition in 1870), published his 'Naturliche
Schopfungsgeschichte,' in which he fully discusses the genealogy of man.
If this work had appeared before my essay had been written, I should
probably never have completed it. Almost all the conclusions at which I
have arrived I find confirmed by this naturalist, whose knowledge on many
points is much fuller than mine. Wherever I have added any fact or view
from Prof. Haeckel's writings, I give his authority in the text; other
statements I leave as they originally stood in my manuscript, occasionally
giving in the foot-notes references to his works, as a confirmation of the
more doubtful or interesting points.

During many years it has seemed to me highly probable that sexual selection
has played an important part in differentiating the races of man; but in my
'Origin of Species' (first edition, page 199) I contented myself by merely
alluding to this belief. When I came to apply this view to man, I found it
indispensable to treat the whole subject in full detail. (2. Prof.
Haeckel was the only author who, at the time when this work first appeared,
had discussed the subject of sexual selection, and had seen its full
importance, since the publication of the 'Origin'; and this he did in a
very able manner in his various works.) Consequently the second part of
the present work, treating of sexual selection, has extended to an
inordinate length, compared with the first part; but this could not be