8o 



MEN DEL ISM 



CHAT. 



grain, when these were so vastl\' outnumbered by 

 normal ones. The ex'idence in this case suggests 

 that two nornial gametes met, that subsequently a 

 radical change occurred in the }'oung zygote, \vhercb\' 

 the normal factor was somehow obliterated. 



The exact point of origin of few, if an\', mutations 



[■'[<:. 17. 



'I'he "'cicliil ' sweut-pca. 



is so well established as that of the cretin. Xc\-er- 

 theless enough is known to show that they frecjuently 

 occiu' in the same wa)' — as rare and isolated instances 

 in a strain of normals, and behaving as simple re- 

 cessives to those normals. Evidently we have not 

 yet found the solution to Plutarch's problem. 



