THE LAWS OF HEREDITY 



the sovereigns of that time were breeding mental 

 monstrosities for a bench show. Their experi- 

 ment shows the eugenic principle inverted. 



But the feature of the pedigree of the de- 

 praved Don Carlos which chiefly concerns us at 

 the moment is the fact that there appear in the 

 table, mingled with the names of the weaklings, 

 the mentally unbalanced, and the morally de- 

 praved, the names of several famous characters, 

 including Charles the Bold of Burgundy, Maxi- 

 milian I of the Holy Roman Empire, Ferdinand 

 and Isabella the Catholics, and the Emperor 

 Charles V. What further excites surprise is that 

 the names of Ferdinand and Isabella appear again 

 and again in the fourth generation, and that in 

 the heritage of Isabella there seems to be an al- 

 ternation of generations between insanity and 

 genius. 



This gives practical illustration of the affinity 

 above referred to between mental aberration 

 and genius of a certain type. It suggests further 

 that genius and mental impairment follow the 

 same law of inheritance. 



There is a growing body of evidence to show 

 that both views are valid. In recent years investi- 

 gation has been made not only on the bad strains 

 of royal pedigree, but on the heredity of genius 

 and of insanity among people in general, and the 

 result is that we are nearer an understanding of 

 this hitherto obscure subject than ever before. 



The puzzling thing has always been that the 

 children of the man or woman of genius very 



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