132 MENDELISM chap. 



hope to come to any conclusion until we have evidence 

 collected by critical and competent observers. 



Though for the present we must regard the case of the 

 negro as not proven, there are nevertheless two others in 

 which the heredity would appear not to follow the Men- 

 delian rule. Castle in America crossed the lop-eared 

 rabbit with the normal form, and found that the Fi ani- 

 mals were intermediate with respect to their ears. 

 And subsequent experiment showed that, on the whole, 

 they bred true to this intermediate condition. The other 

 case relates to Lepidoptera. The speckled wood butter- 

 fly {Pararge egeria) has a southern form which differs 

 from the northern one in the greater brightness and depth 

 of. its yellow-brown markings. The northern form is 

 generally distinguished as var. egeriades. Bateson 

 crossed the southern form from the south of France with 

 the paler British form, and found that the offspring were 

 more or less intermediate in colour, and that in subse- 

 quent generations the parental types did not recur. 

 These cases at present stand alone. It is possible that 

 further research may reveal complications which mask or 

 interfere with an underlying process of segregation. Or 

 it may be that segregation does not occur owing to some 

 definite physiological reason which at present we do not 

 understand. 



And here it is impossible not to recall Mendel's own 

 experiences with the Hawkweeds {Hieracium). This 



