152 HEREDITY IN RELATION TO EUGENICS 



a strain but the strain merely reveals, and does not cause, 

 the weakness. 



That such weakness or Uability to hernia is inherited ad- 

 mits of little doubt. Just how, there is hardly sufficient data 



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Fig. 127 Fig. 128 



Fig. 127. — Pedigree of inguinal hernia. Probably only affected persons 

 (black) are shown. All males have a right handed scrotal hernia and both 

 affected females have a femoral hernia. Couch, 1895. 



Fig. 128. — Pedigree of inguinal hernia (black symbols). F. R.; Rei. 3. 



to determine with certainty. It is probable that a weakness 

 from both sides of the house will yield only weak offspring. 

 This is indicated in Figs. 127, 128; all males have a right 

 handed scrotal hernia and both affected females have a 

 femoral hernia. 



33. Diseases op the Blood 



These are generally classified into two groups; the anemic 

 and the hemorrhagic; in both, the evidence of an inheritable 

 tendency is clear. 



a. Of the Anemic Diseases, chlorosis is the commonest, is 

 found almost exclusively in females, and occurs frequently 

 enough in many or all of the females of one family to render 

 it probable that eventually it will be found to accompany a 

 distinct inheritable weakness.^ A careful study of pedigrees 

 is highly desirable. 



1 Potain (Article, Anemia, Diet, encycl. des sci. med.) says "The children 

 of a chlorotic woman are often all chlorotic — and in certain cases even the 

 male children do not escape." 



