in the force of heredity. When it is considered how rarely such an ancestry produces a great man, it must be fairly evident that his greatness is due to an accidental conjunction of favorable traits, as the modern theory of genetics holds; and that greatness is not due to the inheritance of acquired characters, on which hypothesis Pasteur and Faraday would indeed be difficult to explain.
Cases of this sort, even though involving much less famous people, will be found in almost every genealogy, and add greatly to the interest of its study, as well as offering valuable data to the professional geneticist.
(d) Even if the information it furnishes were more complete, human genealogy would not justify the claims sometimes made for it as a science, because, to use a biological phrase, "the matings are not controlled." The results of a certain experiment are exhibited, but can not be interpreted unless one knows what the results would have been, had the preceding conditions been varied in this way or in that way. These controlled experiments can be made in plant and animal breeding; they have been made by the thousand, by the hundred thousand, for many years. They can not be made in human society. It is, of course, not desirable that they should be made; but the consequence is that the biological meaning of human history, the real import of genealogy, can not be known unless it is interpreted in the light of modern plant and animal breeding. It is absolutely necessary that genealogy go into partnership with genetics, the general science of heredity. If a spirit of false pride leads genealogists to hold aloof from these experiments, they will make slow progress. The interpretation of genealogy in the light of modern research in heredity through the experimental breeding of plants