36 THE TREND OF THE RACE 



normal who mate with the feeble-minded are apt to be people of 

 relatively poor stock. Probably many of them should be classed 

 as high-grade morons, or at least people below the average grade 

 of intellect. A considerable proportion of them carry the germs of 

 other forms of defect and many of them are addicted to alcohol. 

 The individuals designated in the charts as N, with perhaps more 

 of courtesy than they really deserve, are scarcely comparable to 

 the average of the general population. The charts, which are 

 frequently chosen to illustrate striking cases, may give an exag- 

 gerated notion of the frequency with which the matings of feeble- 

 minded and normal produce feeble-minded offspring. However, 

 when one goes over the matings in the Kallikak family where all 

 the known matings are recorded, it will be found that feeble- 

 minded offspring result from over two-thirds of the cases of nor- 

 mal X feeble-minded matings. As we have seen, the mating of 

 normal and feeble-minded among the Hill Folk gave 37.5 per 

 cent of defective offspring. 



It is evident that we need not assume that our inheritance 

 is vitiated to the extent that these studies seem to indicate if 

 we grant that the dominance of mental normality is imperfect and 

 variable. A tendency toward defectiveness is not only subject 

 to various environmental influences both before and after birth, 

 but it is combined with various other hereditary traits in different 

 offspring which could scarcely fail to influence its expression. In 

 the case of the insane diathesis we should expect that such in- 

 fluences would have a profound effect on the manifestation of 

 insanity, and in feeble-mindedness they might well produce 

 differences which would determine whether or not a person were 

 classed as feeble-minded or as normal. 



Both Heron and Pearson have contended with much reason 

 that mental defect varies continuously. There are all grades from 

 the lowest forms of idiots to high-grade morons, and there is no 

 line which can be drawn between the latter and people of normal 

 intelligence. Mental defectiveness is a matter of degree, varying 

 like height, weight, physical strength, hair color and a number of 

 other human qualities, in a manner that permits of no grouping 



