vii] DISPUTED QUESTIONS 87 



lop-eared and short-eared rabbits, young with ears of 

 intermediate length are produced, and these mated 

 together give no evidence of segregation in the next 

 generation. From these and some other similar 

 observations it must be concluded, either that in 

 some cases there is incomplete segregation or even 

 complete fusion of alternative characters, or that 

 what appear to be simple characters are really com- 

 plex, and that the true-breeding intermediates are 

 formed by a new combination of elementary factors. 

 An instance, which is perhaps similar, will be men- 

 tioned in the next chapter in discussing the inheritance 

 of pigment in Man. 



A second question with regard to Mendelian 

 segregation has at present received hardly any 

 answer, namely, whether the apparently ' continuous' 

 variations such as were illustrated by the example of 

 Johannsen's beans (Chap, iv) segregate according to 

 the Mendelian rule. It was seen that each ' pure 

 line/ derived by self-fertilisation from an individual 

 plant, has its own type about which the size of the 

 beans borne by the plant fluctuates ; but it is not 

 known whether, when two plants having different 

 types (modal sizes) are crossed, segregation takes place 

 between the two types in the formation of the germ- 

 cells of the crossed individual. To determine this 

 would naturally require a long and difficult series of 

 experiments, and at present very little is known of 



