BLENDING INHERITANCE 185 



second filial generation 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 , J, f , J, f , }, and f lengths. Not one of 

 these fractional lengths apparently segregated in 

 subsequent 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 | as well as f and f lop lengths would also pro- 

 duce J 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 

 considerable 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 condi- 

 tion 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 



