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THE POPULAR SCIENCE MONTHLY 



Fig. 9. A dark smooth Guinea-pig. 



of rabbits of any desired size within the known limits of variation in 

 size among rabbits, and with any of the conceivable combinations of 

 color factors. Size variation is apparently continuous and its inherit- 

 ance blending, color variation is discontinuous and its inheritance 

 Mendelian. 



Notwithstanding the seemingly radical difference between these two 

 types of inheritance, it is possible that they may, after all, prove to have 



Fig. 10. A white rough Guinea-pig. 



