CHAPTER VII 



SOME DISPUTED QUESTIONS 



IN this chapter will be briefly considered certain 

 questions which either are still quite unsettled, or 

 upon which there is still active disagreement among 

 biologists. It will be convenient to take first some 

 which are closely connected with the Mendelian theory 

 of heredity, and pass on later to others which are 

 related equally to any theory of inheritance which 

 may be adopted. 



One of the chief lines of attack on the Mendelian 

 theory has been the proposition that the absolutely 

 complete segregation of allelomorphic characters in 

 the germ-cells, postulated by that theory, has not 

 been proved. If the theory is rigidly true, then in 

 the case of a tall pea crossed with a short (Chap, v) 

 the homozygous tails and shorts among the offspring 

 of the cross should be as pure for tallness or short- 

 ness as the original parents ; neither character should 



