BLENDING INHERITANCE 179 



tion be called perfect, but it may at least be said that 

 evidence of segregation, that is, a return to one or the 

 other of the parental types, was much less apparent 

 than evidence of blending. 



Furthermore, crosses were made in which lop ears 

 of various fractional lengths were obtained as desired, 

 including |, i, f, i, f , f , and lengths. Not one of 

 these fractional lengths apparently segregated in sub- 

 sequent generations after the Mendelian fashion, but 

 all bred approximately true. 



Moreover, ears of one half lop length, for instance, 

 were obtained in three ways: first, by crossing full- 

 length lops with short-eared rabbits as indicated in the 

 first cross of the case cited above; second, by crossing 

 one half lop lengths together, demonstrated by the 

 second cross in the illustrative case given, and third, 

 by mating J and f lop lengths. Theoretically, -J and J- 

 as well as f and f lop lengths would also produce 

 \ lop lengths, for in all of the crosses that were made 

 the length of ear behaved in a blending fashion. 



These results were based, not upon a single measure- 

 ment of each specimen, which might be open to con- 

 siderable error, but upon daily measurements from the 

 time the rabbits were two weeks old until their ears 

 ceased to grow at about twenty weeks. The growth 

 curves drawn from these daily measurements showed 

 continually an intermediate or blending condition in 

 progeny derived from diverse parents. 



A Mendelian explanation of this apparently excep- 

 tional case of blending inheritance has been suggested 

 by Lang based upon the result of Nilsson-Ehle's dis- 



