88 THE MENDEL JOURNAL 



or thirty-seven per cent, of night-blind persons 

 instead of fifty per cent. Too much stress must not 

 be laid upon this numerical difference. It must be 

 remembered that segregation and gametic purity 

 can exist notwithstanding that the proportions do 

 not accurately accord with expectation. Factors of 

 which we have no knowledge may be at work, dis- 

 turbing these proportions in some families or genera- 

 tions, and leaving them undisturbed in others. No 

 one with any real experience of living organisms, 

 including human nature, doubts it is a fact which 

 should be constantly held in view that living gametes 

 within a living zygote are not marbles in a bag. 

 The latter can be shaken up to ensure an uniform dis- 

 tribution of the black and white ones, but gametes 

 and human nature cannot be so treated ; we must 

 accept them as Nature listeth they shall be. And 

 this particular case is instructive, for there are good 

 reasons to believe that the number of abnormals 

 recorded does not represent the true number. The 

 chief of these reasons arises from the promptings of 

 a natural human weakness, i.e., a reluctance to admit 

 the existence of physical defects, and additionally 

 there is upon the part of the women a very laudable 

 desire not to jeopardise their chances of becoming 

 wives and mothers. For the learned Cure who is 

 familiar with the living descendants of this stock, 

 and who has contributed to the construction of the 

 pedigree, says : " It is considered as prejudicial to 

 the establishment of children " to be afflicted with 

 this disease, " and it is therefore apt to be concealed." 



