308 UNIVEESITY OF VIRGINIA PUBLICATIONS 



The additional evidence on left-handedness here presented establishes 

 beyond doubt, I think, my earlier contention, that left-handedness is 

 hereditary. The practical identity of the proportion of left-handed to 

 right-handed individuals of fraternities of more than four individuals, of my 

 two studies — and the corroborating evidence of Hurst — indicates very 

 strongly that left-handedness behaves in inheritance as a Mendelian reces- 

 sive. There appears meager evidence that true ambidexterity is inherited 

 as such, representing perhaps a balanced state of dominance and reees- 

 siveness. 



The questions touching the phylogenetic origin of right-handedness; 

 and the fundamental causes underlying left-handedness; and the nature and 

 complete behavior of the hereditary factor or complex of factors, are 

 approached in an attitude of open-mindedness to all possibly pertinent 

 evidence. The effort, however, it must be admitted, soon leads to specula- 

 tion, and yields no definite results. Decision halts between the idea of the 

 inheritance of an acquired character (i.e., by tradition and training), 

 and that of a germinal variation causing vascular alterations. The rela- 

 tion of ambidexterity to right-handedness and left-handedness also remains 

 obscure. , 



PULMONARY TUBERCULOSIS. 



With the exception of case, pedigree chart, figure 36, the family his- 

 tories here considered were secured for me by Dr. Lewis Booker of the 

 North Carolina Tuberculosis Sanatorium, at Montrose. 





dj.^Q, cf.?y- cl-^1 





Fig. 36 Pulmonary Tuberculosis. 



Case, pedigree chart, figure 36, shows a three-generation family history 

 of tuberculosis. This case suggests the recessiveness of the tuberculosis 



