112 THE TREND OF THE RACE 
mindedness of various grades is recessive or partly recessive to 
normal mentality, and if the lower grades of feeble-mindedness 
tend to be recessive to the higher forms, we should expect to find 
average ability recessive to superior ability. It is not an easy 
matter, especially when dealing with incomplete records and with 
characters which (like musical and artistic ability) are strongly 
influenced by family traditions, to determine whether a given 
character is dominant or recessive. The test of recessiveness is 
given if the matings of parents both of whom have the character 
in question produce children all of whom inherit this character. 
But this test is never completely satisfied, although non-conform- 
ing cases might conceivably be explained. 
We should get much the same results if the character were 
dominant and several determiners were concerned in its produc- 
tion as in the case of the dark color of various kinds of wheat and 
oats. On the whole, I believe the inheritance of exceptional 
ability is best explained—though I cannot here give in detail the 
evidence for this conclusion—on the assumption that it depends 
upon many factors which behave as dominants to those which 
give rise to ability of an inferior kind. The fact that parents of 
superior ability produce, though only occasionally, offspring 
which, although normal and healthy, never come near to measur- 
ing up to the intellectual capacity of their parents, is quite in 
accord with this view, while opposed to the theory of the recessive 
nature of superior mental endowments. Results of negro-white 
crosses yield confirmatory evidence of the same view. 
Perhaps the doctrine that genius or great ability is a sort of 
anomaly dependent upon some defect of the germ plasm has been 
fostered by the rather prevalent notion that genius tends to be 
associated with insanity. The doctrine expressed by Dryden in 
the lines; 
“Great wits are sure to madness near allied, 
And thin partitions do their bounds divide,” 
not only expressed a popular conviction, but the sober conclusion 
of many scientific men who have devoted especial attention to the 
