Twenty ninth meeting. 



Cornell University Medical College, Nezv York City. May 20, 

 1908. Silas P. Bee be in the chair. 



59 (315) 



Heredity of some human physical characteristics. 



By C. B. DAVENPORT. 



\From the Carnegie Institution of Washington; Station for Experi- 

 mental Evolution. Cold Spring Harbor, Long Island, N. K] 



It has already been shown 1 that dark brown eye color is a 

 Mendelian dominant to gray and gray to blue. It now appears 

 that the form of the hair also follows Mendel's law. Thus, if the 

 three grades of straight, wavy and curly be recognized then straight 

 hair is recessive to curly. But " wavy " is peculiar in that it ap- 

 pears to be a hybrid or heterozygous condition indicating the 

 presence of both straight and curly germ cells. It follows from the 

 foregoing facts that two blue eyed, straight haired parents will 

 have only children like themselves ; but two brown eyed, curly 

 haired parents may have a variety of these characters in their 

 families. Again, the records collected by Mrs. Davenport and 

 myself show that two flaxen haired parents have flaxen haired 

 children and probably only such ; two parents with light brown 

 hair have children with hair of that color and lighter, but not 

 darker ; while children of two parents each with dark brown or 

 black hair produce children with all of the varieties of hair color. 

 Also two golden haired parents have only golden haired children 

 and none with red hair. Consequently two blue eyed, flaxen or 

 golden and straight haired parents will have only children like 

 themselves. And the reason is that the germ cells as well as the 

 somatic cells of such parents lack the dark and curly characters. 



In the foregoing cases of heredity the more advanced condi- 

 tion is dominant over the less advanced. This is often, if not 

 usually, true and this rule enables us to predict the outcome of 



Gertrude C. and Charles B. Davenport, Science, November I, 1907. 



(101) 



