CHAPTER V 



EVOLUTION OP NEW KACES BY LOSS OB GAIN OF 

 CHARACTERS 



OUR knowledge of Mendelian phenom- 

 ena is most complete in the case of 

 color-inheritance. We find that the 

 flower-colors of plants and the coat-colors of 

 mammals are alike complex, and that what 

 seem at first sight simple results may really 

 depend on several independent factors acting 

 conjointly. By analysis of such complex cases 

 we are able to gain some idea of what the 

 probable course of evolution has been in the 

 production of the color varieties found among 

 cultivated plants and domesticated animals. 



Thus among rodents (mice, rabbits, guinea- 

 pigs) the coat is grayish, consisting of black, 

 brown, and yellow pigments mingled together 

 on the same individual hair in a pattern of 

 greater or less complexity. 



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