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THE POPULAR SCIENCE MONTHLY 



Fig. 4. A Geoup of thuee Young, produced by the pair of albinos 

 shown in Figs. 2 and 3. 



trast to the doubleness (duality) of the individual receives the fullest 

 confirmation from experimental breeding. 



If we mate a pure-bred black guinea-pig with a white one, the 

 young are all black pigmented. This result seems to violate the prin- 

 ciple previously stated that both parents contribute equally in heredity ; 

 in reality, however, that principle is not violated. The white parent 

 has contributed its own character to the offspring, but that contribu- 



