r
hand some writers assure us that cousin marriages are even more
prolific and less liable to sterility than the average.

[Footnote 43: See Darwin, "Marriages between First Cousins in England
and Their Effects," _Journal of Statistical Society_, June, 1875, p.
178.]

[Footnote 44: Boudin, "Croisement des familles, de races et des
especes." In _Memoires de la Societe d' Anthropologie_, vol. i, p.
518.]

The most important statistical investigation was made by G.H.
Darwin.[45] From his genealogical data he compiled the following
table:

TABLE XVI.
------------------------------------------------------------------------
| | Average | |Ave. no.
| | number | Per cent |sons to
|Number of | sons to | sterile |fertile
|marriages.| marriage. | marriages. |marriage.
------------------------------------------------------------------------
Not consanguineous | 217 | 1.91 | 15.9 | 2.26
Parents 1st cousins[A] |97 to 105 |2.07 to 1.92|14.7 to 20.9| 2.43
One parent offspring of | | | |
1st cousin marriages. | 93 | 1.93 | 17.2 | 2.34
------------------------------------------------------------------------
[A] Eight cases of doubtful fertility.

[Footnote 45: Op. cit., p. 181.]

It will readily be seen that the conclusion is negative, since the
variation is slight, but the higher fertility of the cousin marriages
is interesting.

On the other hand de Lapouge quotes a case of a community founded two
centuries ago by four families and populated almost entirely by their
descendants, in which from 1862 to 1886 there were 273 marriages of
which 63 were consanguineous and 26 were between first cousins. Among
the non-consanguineous 3 per cent were uniparous, as against 7.95 per
cent among the consanguineous. 7.5 per cent of the non-consanguineous
were sterile as against 16 per cent of the consanguineous.[46] The
importance of these percentages is impaired by the fact that they
involve only five uniparous families and ten sterile ones, and that of
these latter only five were sprung from first cousins.

[Footnote 46: De Lapouge, _Les Selections Societies_, p. 196.]

It is almost impossible to get any accurate statistics of sterility
from genealogies, for when no children are given