Admiral Coligny. Frederick I married his second cousin, daughter of
the Duchess Sophia of Brunswick, and a descendant of William.
Frederick William I married his first cousin, Dorothea, granddaughter
of Sophia, and also a descendant of William the Silent. Unfortunately
the Hohenzollern line was continued by a mediocre brother of Frederick
II, but through his sister, Queen Ulrica, the line of genius lasted
still another generation to Gustavus III of Sweden.]

The ills which have at one time or another been attributed to
consanguineous marriage include nearly all those which cannot
otherwise be satisfactorily accounted for. But with the progress of
pathology the list has greatly been reduced: for instance, cretinism
is now known to be a product of local conditions. The remaining
counts in the indictment against consanguineous marriage may roughly
be classified as: 1. The production of infertility, some forms of
physical degeneracy, and deformity. 2. The production or aggravation
of mental and nervous disorders. 3. The production of certain defects
in the organs of special sense. These three divisions will be
discussed separately.


1. INFERTILITY AND DEGENERACY

Although there has never been any considerable evidence for the first
of these charges, it has frequently been repeated. Professor
Montegazza of the University of Pavia collected data in regard to 512
cases of consanguineous marriage of which between 8 and 9 per cent
were sterile, and with this basis he asserts that sterility is the
only fact which can safely be deduced from his cases, since it cannot
be hereditary.[43] But if in the nature of things absolute sterility