COLOR. 



Table 33. 



67 



HEREDITARY FACTORS AND THE PHYSIOLOGY OF PIGMENT. 



The definitions which have been given for the hereditary factors are 

 based largely on the colors as seen without a microscope. It would be 

 very desirable, however, to correlate color factors accurately with the 

 variations in quality and quantity of the actual pigments and ultimately 

 with the physiology and chemistry of pigment formation. 



Considerable progress has been made in recent years in the study of 

 the chemistry of melanin pigments. The melanins are amorphous 

 granular pigments found throughout the animal kingdom. A large 

 number of researches have established the fact that substances which 

 closely resemble the natural melanins can be produced by the action of 



