CHARACTERS KNOWN TO BE INHERITABLE 397 



Characters Known to be Inheritable. — The following table 

 indicates some of the characters in man that have been proved to 

 be inheritable according to the laws of Mendel. 



Dominant Character 

 Black or brown eye 

 Pigmented iris 

 Dark skin 

 Curly hair 

 Dark hair 



Congenital white lock 

 Beaded hair 

 Nervous temperament 



Recessive Character 

 Blue or gray eye 

 No pigment in iris 

 Light skin 

 Straight hair 

 Light hair 

 Normal hair 

 Straight hair 

 Phlegmatic temperament 



More study has been given to the inheritance of defects and 

 susceptibility to diseases. Although these studies have been in 

 progress only a few years, the following list probably is approxi- 

 mately correct. 



Dominant Character 

 Two- jointed fingers 

 Extra digit 



Congenital cataract of eye 

 Abnormally short limbs 

 Hairless or toothless condition 

 Spotted hair coat 

 Huntington's chorea 



Recessive Character 

 Normal fingers 

 Normal number of digits 

 Normal condition of eye 

 Normal limbs 

 Normality 

 Normality 

 Normality 



Cases where the defect is recessive to the normal condition are 

 much more difficult to find, but the following examples appear to 

 be well established, according to Guyer : 



Dominant Character 

 Normal pigment 

 Normal intellect 

 Normal intellect 



Normality 

 Normality 

 Normality 

 Normality 

 Normahty 



Recessive Character 



Albino skin 



Feeble-mindedness 



Alcoholism (when based on feeble- 

 mindedness) 



Susceptibility to cancer 



Tendency to asthma or hay fever 



Probable susceptibility to tuberculosis 



Chorea (St. Vitus's dance) 



Lack of muscular control and several 

 other less known diseases. 



