84 



REPORTS ON INVESTIGATIONS AND PROJECTS. 



It was found that alkali in excess of 0.2 per cent concentration (calculated 

 as sodium hydrate) readily destroyed the greater portion of the pigment 

 molecule and caused a great loss in both the nitrogen and hydrogen content. 

 The yields of the melanin obtained by the different methods are given in 

 table I and the analytical data is shown in table 11. 



In addition to this work the pigmentation of the meal-worm (Tenebrio 

 molitor) was studied and was found to be due to the interaction of an oxi- 

 dase and an oxidizable chromogen. 



A study of dominant and recessive white was also undertaken and the con- 

 clusions arrived at were that the plumage or hair of both varieties do not 

 differ, chemically, to any appreciable extent, i. e., the dominant whites do not 

 possess a pigment which is lacking in the recessive whites, but that an in- 

 hibitory enzyme is probably present in the dominant whites which, acting as 

 the determiner, prevents pigment formation, while the recessive whites have 

 neither the power to form melanin nor the ability to inhibit its formation. 



Table I. — Percentage yields of ash-free melanin obtained from black wool 

 by extraction with increasing strengths of alkali. 



Table II. — Analytical data obtained by a study of the pigments isolated by 



the different methods. 



HUMAN HEREDITY. 



In connection with the eugenics section of the American Breeders' Asso- 

 ciation and its committees, the application of the new principles of heredity 

 to man is making satisfactory progress. Mrs. Davenport and the Director 

 have just completed a paper on "Skin-color in man," in which progress is 

 made on the following points : 



(a) It is shown that skin coloration of white races is not a blend, but 

 segregates and follows the general law, first pointed out by us in the case of 

 hair-color, that, in general, the skin-color of the children is not darker than 



