BLENDING INHERITANCE 187 



nants would be extremely unlikely, and it might easily 

 be mistaken for a mutation or a freak. Apparent 

 blends of all intermediate degrees, however, would be 

 sure to appear. Yet these are not blends in the 

 "melting-pot" sense at all, but strictly cases of 

 Mendelian dominance and segregation. 



9. THE APPLICATION OF THE NILSSON-EHLE EXPLA- 

 NATION TO THE CASE OF RABBIT EAR-LENGTH 



The so-called blending rabbit ears, along with other 

 similar cases, can now be made to fall into line, as 

 pointed out by East and by Lang, with the Mendelian 

 law of segregation. 



If we assume that the long ear of the lop rabbit has 

 only three independent but equal determiners for excess 

 length, the case becomes one of Mendelian trihybridism 

 with cumulative factors, which works out like Nilsson- 

 Ehle's red-kerneled wheat in the following manner: 



In general the average for full lop ear-length may 

 be placed at 220 mm. and for the ordinary short- 

 eared rabbit 1 at 100 mm. The difference, or the excess 

 length of the lop ear, is 120 mm., which, according to 

 the trihybrid formula, corresponds to the six doses of 

 the character symbolized in the upper left-hand square 

 in Figure 39 by six large screw-heads, three coming 

 from each parent respectively. If all of these inde- 

 pendent determiners are* equal as regards excess ear- 

 length, each factor would represent an excess of 20 mm. 



J Not the Belgian hare, as cited in the illustration given in 

 Figure 36. The Belgian hare has typically a somewhat longer 

 ear than the ordinary short-eared rabbit. 



