592 



SCIENCE 



[N. S. Vol. XXVI. No. 670 



Abbreviations: Br, brown; DkBr, dark brown; Blk, black; D, dominant; DR, dominant and re- 

 cessive (heterozygous) ; R, recessive. 



Colors in parentheses are recessive; without a ? means observed, with a ? means hypothetical. 

 Quotation marks means doubt if the term is used with precision. Double query, doubt as to cor- 

 rectness of color assigned. 



It remains to consider the behavior of gTay 

 in inheritance. Upon tabulating the crosses 

 of blue with gray we find that gray domi- 

 nates over blue. This is true, for example, 

 in the Al., Bu., He., Lu., McC, Hi., Va. and 

 Wal. pedigrees given in the Appendix. In 

 families where blue X gray parents have a 

 blue-eyed child (Br., Oa., Vo. families) the 

 gray is doubtless heterogametous, containing 

 recessive blue. Again, when both parents are 

 gray-eyed they have produced 9 gray-eyed to 

 2 blue-eyed children — indicating that both 

 grays are DE (containing recessive blue) ex- 

 pectation being three gray to one blue. Con- 

 sequently, gray or partial pigmentation is 

 dominant over the pigmentless blue and the 

 occasional enumeration (Ma. family) of de- 

 scendant of two blue-eyed parents as " blue- 

 gray " or " gray " is due to a slight inaccuracy 

 of classification. On the other hand, gray is 

 recessive to brown (La. family), i. e., a slight 

 pigmentation to an extensive one. 



The facts brought out by these statistics 

 show, first, that there are two principal classes 

 of eye-color — brown and blue: that brown 

 varies in intensity from black to light brown; 

 that blue or absence of pigment varies from 

 pale to deep ; that blue is frequently imperfect 

 owing to the presence of specks or patches of 

 pigment — the " gray " or " hazel " color ; that 

 blue is recessive to gray and gray is recessive 

 to brown. 



The practical applications of these results 



to human marriage are as follows : Two blue- 

 eyed parents will have only blue-eyed children; 

 two gray-eyed parents will have only blue-eyed 

 and gray-eyed but not brown- or black-eyed 

 children; brown-eyed parents may have chil- 

 dren with any of the colors of eyes. Gray 

 and blue-eyed parents will tend to have either 

 gray-eyed children only or an equal number of 

 gray- and of blue-eyed children according as 

 the gray-eyed parent is homozygous or heter- 

 ozygous. When one parent has blue eyes and 

 the other brown the children will be all brown- 

 eyed, if the brown-eyed parent is homozygous — 

 otherwise they will have eyes of various colors 

 according to the gametic constitution of the 

 brown-eyed parent. In case one parent has 

 gray eyes and the other brown we may have the 

 following eases in the oilspring: all of them 

 brown-eyed (dark parent homozygous) ; 50 per 

 cent gray and 60 per cent, brown (brown par- 

 ent heterozygous in gTay or blue) ; 25 per cent, 

 blue, 25 per cent, gray and 50 per cent, brown 

 (both parents containing recessive blue germ- 

 cells). 



Gertrude C. Davenport 

 Charles B. Davenport 



the nomenclature of dextral, sinistral and 

 attentional organs and functions 

 In the Popular Science Monthly, August, 

 1904 (republished in Biographic Clinics, Vol. 

 m.), I made some suggestions as to the 

 nomenclature of the organs and functions 



