40 THE TREND OF THE RACE 
influence on the mentality of the individual concerned, it is a 
priori very improbable that the inheritance of mental defect is 
adequately describable in simple Mendelian terms. Most of the 
charts which group human beings categorically as feeble-minded 
or normal, as we class mice as gray or albino, take no account of 
the varied manifestations of mentality which really occur. They 
are liable to give a false or misleading appearance of simplicity 
which in fact has no existence. 
Whether the inheritance of mental defect follows simple or 
complex Mendelian formulas, or whether, indeed, it may not take 
place according to the older conceptions of blending inheritance, 
makes comparatively little difference in the practical treatment of 
hereditarily defective persons. The fact that defective mentality 
is strongly transmitted is established beyond the possibility of 
sane objection, and the particularly disastrous results that are 
pretty sure to follow from the mating of two mental defectives 
have certainly been made sufficiently impressive by the work of 
recent investigators. 
EPILEPSY 
Although Morel questioned its hereditary transmission, there 
is now a general consensus of opinion that epilepsy is often 
inherited. This dreaded malady occurs in a variety of forms 
(petit mal, grand mal, Jacksonian epilepsy, etc.) and is frequently 
associated with other forms of defect such as feeble-mindedness 
and insanity. Many cases are doubtless to be attributed to 
trauma, disease and alcohol, although a part of such cases prob- 
ably have a basis in inheritance as well. Concerning the propor- 
tion of cases attributable to heredity I can do no better than to 
quote from Barr (Mental Defectives, p. 212) ‘Hammond in a study 
of 171 epileptics, finds heredity a cause in 45,—21 of these proving 
direct; Echeverria gives 26 per cent of 306 as descendants of 
epileptic parents. Delasiauve found the same in 33 out of 300 
cases, and Herpin ro in 68 cases. . . . Hamilton states that fully 
50 per cent of his 980 cases are attributable to heredity. Gowers 
