18 THE TREND OF THE RACE 
Table of Human Hereditary traits 
Dominant Characters Recessive or Partly Recessive 
Characters 
Dark hair Light hair 
Lack of hair (hypotrichosis), Beaded hair Normal 
Dark skin Light skin 
Pigmented skin Albinism 
Partial albinism, keratosis, ichthyosis, tylosis, Aieaeat cite. 
epidermolysis 
Dark eyes Light eyes 
Cataract, pigmentary retinitis, coloboma? 
} 
1 
glaucoma, displaced lens, nystagmus i Normal eyes 
Tall stature (in part) Short statute (in part) 
Achondroplastic dwarfism Normal. 
Polydactylism, brachydactylism, syndactylism, } Nigemnal 
Fragility of bone, Symphalangy, exostoses 
Normal Deaf mutism, otosclerosis 
Hapsburg lip, Hare lip (imperfect dominant?) Normal 
Diabetes Normal 
Superior mentality Inferior mentality 
| Feeble-mindedness, epilepsy, 
insanity, Meniere’s disease, 
chorea, multiple sclerosis 
Huntington’s chorea, muscular atrophy Normal 
Normal mentality or nervous condition 
Sex Linked (mostly recessive) Characters 
Color blindness, night blindness, hemophilia, 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 
