It has often been maintained that the qualities of higher forms of man are exhausted in a few generations, while the mass of mediocrities continually produce new genius. The fact that the descendants of distinguished men are often mediocre and that remarkable men suddenly arise from the common people, appears at first sight to support this superficial assertion. It is forgotten, however, that in a people whose average mass consists of thousands or millions of individuals, while men of higher powers are only counted by units or dozens, all this arithmetic is reduced to absurdity by the inequality of numbers, as soon as the law of heredity is understood. To make a more exact calculation, it would be necessary to compare the number of superior men who have arisen from some hundreds of the most distinguished families of a country with that of distinguished men who have arisen from some millions of the rest of the people, and then calculate the percentage. It is also necessary to take into account the means employed in the education of the individuals. If education is obligatory and gratuitous in a country, this factor will have less importance. Another error which is committed in such cases is to neglect the influence of the maternal lineage. A common woman will lower the level of the offspring of a distinguished husband, and inversely. In his "History of Science and Scientists" _Alphonse de Candolle_ has given irrefutable proof that the posterity of high-class men furnishes a great number proportionally of men high class in their turn, compared with that of the average population. This shows the value of the usual twaddle concerning this question. It is inconceivable that the laws of heredity should make an exception of the mental qualities of man. Moreover, the most deceptive point is the contrast of a man of genius with his children, who do not rise to his standard because they represent a combination of his ancestral energies with those of their mother. This contrast makes the children appear unfavorably, while the public has a general tendency to exaggerate the value of a great man. The theory of the mneme throws light on this subject, by introducing a new factor in the question, that of ecphoria of the cerebral engrams of the ancestors, accumulated in the hereditary mneme. =Heredity of Acquired Characters.=--While _Darwin_ and _Haeckel_ affirmed the possibility of the heredity of characters acquired during life by different tissues, for instance the brain, _Weismann_ limits the possibility to everything that can modify the nucleoplasm of the germinal cells. We must first eliminate the question of the phenomena of blastophthoria, which we shall consider next, and which _Weismann_ was, I think, the first to comprehend, without giving them the name.