Paul Broca,
On the Phenomena of Hybridity in the Genus Homo
“ It is, therefore, unnecessary that in order a mixture should be eugenesic the fecundity of the cross-breed should be absolutely equal to that of individuals of pure blood. Had it been demonstrated by strict numbers, that a mixed race, by the simple fact of intermixture breeds less rapidly than the two parent races, and were it demonstrated that it presents a greater number of cases of sporadic sterility, it would by no means result from it that this mixed race is incapable of maintaining itself and increasing by itself. ”
