| Self-fertilization prevented (average of nine families) | 53.5 hi pro ha. |
| Self-fertilized (average of ten families) | 25.3 " " " |
| F1 hybrid (average of six families) | 59.2 " " " |
| F2 hybrid (average of seven families) | 38.8 " " " |
It is well-known to what degree inbreeding is practised in reigning families. We show as an example for this, Chart C 112, the pedigree of the Archduchess Maria de los Dolores of Tuscany, exhibited by Dr. Stephan Kekule von Stradonitz, and Chart C 113 of the same exhibitor, pedigree of Ptolemäus X. Soter II. (Lathros), and Chart C 114, pedigree of the celebrated Cleopatra. Though with Ptolemäus X. the effect of sexual reproduction in bringing about new combinations of hereditary units was very limited, since the couple, Ptolemäus V. Epiphanes and Cleopatra Syra having produced all the germ cells from which he developed, he appears, nevertheless, to have been a perfectly normal being. In his granddaughter Cleopatra certainly much "extraneous blood" circulated.
Even where there is no high degree of inbreeding, the individuals of a people are much more closely related to each other than is generally assumed. Table C 115, "theoretical number of ancestors," shows that, assuming the duration of one generation to be 35 years, and that no marriages between relations have taken place, the number of the ancestors of a man living now would have been eighteen billions in the year 0 a.d. In reality the germanic race, wandering west, probably only numbered hundreds of thousands. This phenomenon of "ancestral loss," as Ottokar Lorenz calls it (that the number of real ancestors is much smaller than those theoretically possible), can be illustrated in the pedigrees of the reigning houses.
We have in Table C 116 an analysis of pedigree of Emperor William II., after Ottokar Lorenz. Investigations show that twelve generations back the real number of his ancestors amounts to only one-eighth of the possible figure. Only 275 persons have actually been found because in the older lines, the bourgeois element, of which no record can be found, has had a very large share.
Very little knowledge exists concerning the effect of the crossing of races in man. On the whole it appears not to be favourable, if it is a question of crossing of races from far apart, even in purely physical respects. An example of harmful influence is given in v. d. Velden's Table C 117—"Fertility and Health in relation to the crossings of races."