H. H. Newman 



35 



this mode of inheritance will be found, in the near future, to be inucl> 

 more common than now appears to be the case. 



It is an interesting thought that a specific defect in the adult may 

 be due to an equally specific defect in a single chromosome of the germ 

 cell. Evidently any defect in the X element, assuming that the latter 

 is the seat of the factors responsible for the various defective conditions 

 listed above, must be as distinct and specific as is the condition for 

 which it becomes responsible in the adult. One might, on the other 



Zygotes 



Gametes X 



Zygotes 



Gametes X 



Zygotes XX x X X 



Fig. 2. (Explanation on p. 38.) 



hand, conceive germinal deficiency as due to a generalized metabolic 

 weakness of the X element, and might assume that the particular form 

 of adult deficiency arising from this situation depends on the specific 

 peculiarity of the particular line of germ plasm in which the germinal 

 deficiency arose. In this way one simple type of germinal defect 

 might in one family result in a complex of optic defects and in another 



as haemophilia or muscular atrophy. 



3-2 



