i8 



THE TREND OF THE RACE 



Table of Human Hereditary traits 



Dominant Characters 



Dark hair 



Lack of hair (hypotrichosis), Beaded hair 



Dark skin 



Pigmented skin 



Partial albinism, keratosis, ichthyosis, tylosis, ' 



epidermolysis 

 Dark eyes 

 Cataract, pigmentary retinitis, coloboma? | 



glaucoma, displaced lens, nystagmus J 



Tall stature (in part) 

 Achondroplastic dwarfism 

 Polydactylism, brachydactylism, sjoidactylism, | 



Fragility of bone. Symphalangy, exostoses J 

 Normal 



Hapsburg lip. Hare lip (imperfect dominant?) 

 Diabetes 

 Superior mentality 



Normal mentality or nervous condition 



Recessive or Partly Recessive 



Characters 

 Light hair 

 Normal 

 Light skin 

 Albinism 



Normal skin 



Light eyes 



Normal eyes 



Short statute (in part) 

 Normal 



Normal 



Deaf mutism, otosclerosis 



Normal 



Normal 



Inferior mentality 

 [ Feeble-mindedness, epilepsy, 

 \ insanity, Meniere's disease, 

 [ chorea, multiple sclerosis 



Normal 



Huntington's chorea, muscular atrophy 



Sex Linked (mostly recessive) Characters 

 Color blindness, night blindness, hjemophiha, neuritis optica, Cower's muscular 

 atrophy 



Certain characters, such as skin color in negro-white crosses, 

 appear to form permanent blends, but as Davenport has attempted 

 to show, this may be a complex case of Mendelian transmission 

 in which a considerable number of determiners for skin color are 

 involved. The great variability in the skin color of mulattoes 

 has been appealed to in support of this view. Cases of complex 

 Mendelian transmission are especially difficult to analyze in man 

 and we may have to judge them in the light of analogy with what 

 occurs in the lower animals. With the progress of genetics more 

 and more success is being attained in the resolution of complex 

 and apparently irreconcilable cases in terms of Mendelian prin- 

 ciples. As we learn more of inheritance in man, the more we find 

 that it falls into line with what is known of inheritance in the 



