PHENOMENA OF INHERITANCE 293 



ear length in rabbits, is not due to a single fac- 

 tor, as in the case of Mendel's tall and dwarf 

 peas, but to several factors. Consequently in 

 the formation of the germ cells there is not a 

 clean segregation of all the factors for tallness 

 or large size or long ears in half the germ cells 

 and their total absence in the other half of 

 those cells, but some of these factors go into 

 certain cells and others into others, as in the 

 case of dihybrids, trihybrids or polyhybrids. 

 As a result offspring appear more or less in- 

 termediate in size between their parents. 



Thus it is possible to explain even "blend- 

 ing" inheritance as due not to the real fusion 

 or blending of inheritance factors but to vary- 

 ing combinations of numerous or multiple fac- 

 tors, according to the Mendelian rules. The 

 Mendelian principle of segregation has been 

 found to be of such general occurrence that 

 there is a strong inclination among Mendel- 

 ians of the stricter sort to make it universal, 

 and to explain all cases of "blending" inheri- 

 tance as due to incomplete dominance and to 

 multiple factors. Whether or not such at- 

 tempts may prove completely successful it is 

 still too soon to say. 



