240 INBREEDING AND OIJTBREEDINa 



, be admitted, but does anyone believe tbat these families 

 would have been a credit to the communities harboring 

 them if the environment were changed. It was tried many 

 times and failed. No ! What happened in thesQ cases was 

 the establishment of near-homozygous races having a bad 

 heredity. The result of inbreeding where the germ plasm 

 is bad stands forth as a terrible example. What would 

 have happened had there been no isolation would have 

 been the oontamiaation of good blood lines. In fact, cer- 

 tain illegitimate sub-strains in these clans did stand out 

 above their relatives. Was this not due to a better endow- 

 ment being brought in from the alien male? 



The traits just discussed, at best mere uselessness or 

 lack of capacity, seem to be somewhat less complex in 

 their heredity than those leading to marked superiority, 

 if one may judge by the seeming ease with which they are 

 concentrated. Other undesirable mental characteristics 

 appear to be still less complex. These are f eeble-minded- 

 ness and the conditions related to it. Goddard*^ has 

 studied 327 family histories in which feeble-mindedness 

 entered. Somewhere between 50 per cent, and 75 per cent, 

 of these family trees show distract evidence of the heredi- 

 tary nature of the defect. There were 144 matings of 

 feeble-minded with feeble-minded producing 482 children 

 of which all but 6 were feeble-minded. These few excep- 

 tions to the expectation for the union of two Mendelian 

 recessives may reasonably be explained by assuming there 

 is a paternity other than that assigned. Other types of 

 mating come just as close to Mendelian expectancy, al- 

 though Goddard himself has failed to analyze them prop- 

 erly by not correcting for the necessary omission of 

 heterozygous matings having no feeble-minded' children. 

 We may, therefore, conclude that feeble-mindedness is 



