No. -YA6] 



COLOR INHERITANCE 



467 



granules; and the numerical point at which the process 

 stops determines the color of the skin. But thought of in 

 terms of greater and lesser ability for tyrosin production 

 (intervention of a tyrosinase-producing factor would 

 modify the results, but not fundamentally alter the 

 mechanism of inheritance) ; and attributing such factor to 

 a specific cell-organ which may be a chromosome or part 

 of such ("teleomorph"— Spillman), the segregation 

 noted by the Davenports becomes as intelligible as other 

 Mendelian phenomena. From the standpoint of the num- 

 ber of granules some mulatto skins are certainly different 

 from a "blend" between negro and white, and this is true 

 in the direction both of more and of less-from the stand- 

 point of the amount of pigment some mulattos are iden- 

 tical, on the one hand, with negros and on the other with 

 brunets— and evidences a measure of segregation of 

 "strong melanogenesis" and "slight melanogenesis." 



A plausible interpretation of Karg's experimental find- 

 ings might be made on the basis of a larger and smaller 

 amount of tyrosinase in negro and white blood, respect- 

 ively — or more likely perhaps on the basis of more and 

 less pronounced stimulation by negro and white blood, 



respectively, to tvrosin production. 



Tlu. occurrence of melanotic sarcomata in albinos and 



horses there is present a white melanin— rendered quite 

 doubtful by Gortner's recent work— the end-result of an 



oxidation process of tyrosin, the p 



